Material for organic electroluminescence device and organic electroluminescence device

ABSTRACT

An organic electroluminescence device employing a specific biscarbazole derivative having a cyano group as a first host and a compound having both a carbazole structure and a nitrogen-containing aromatic heteroring as a second host. The organic electroluminescence device has a prolonged lifetime.

TECHNICAL FIELD

The present invention relates to organic electroluminescence devices.

BACKGROUND ART

By applying voltage to an organic electroluminescence device (alsoreferred to as “organic EL device”), holes from an anode and electronsfrom a cathode are injected into a light emitting layer. The holes andelectrons injected into the light emitting layer recombine to formexcitons. The singlet exciton and the triplet exciton are formed at aratio of 25%:75% according to spin-statistics theorem. Since thefluorescence utilizes the emission from singlet excitons, it has beenknown that the internal quantum efficiency of a fluorescent organic ELdevice is limited to 25%. In contrast, since the phosphorescenceutilizes the emission from triplet excitons, it has been known that theinternal quantum efficiency of a phosphorescent organic EL device can beincreased to 100% if the intersystem crossing occurs efficiently.

In the development of known organic EL devices, an optimum device designhas been made depending upon the emission mechanism such as fluorescenceand phosphorescence. It has been known in the art that ahigh-performance phosphorescent organic EL device cannot be obtained bya mere application of the fluorescent technique to the phosphorescentdevice, because the emission mechanisms are different from each other.This may be generally because the following reasons.

Since the phosphorescence utilizes the emission from triplet excitons, acompound with larger energy gap is required to be used in the lightemitting layer. This is because that the singlet energy (energydifference between the lowest excited singlet state and the groundstate) of a compound is generally larger than its triplet energy (energydifference between the lowest excited triplet state and the groundstate).

Therefore, to effectively confine the triplet energy of a phosphorescentdopant material within a device, a host material having triplet energylarger than that of the phosphorescent dopant material should be used inthe light emitting layer. In addition, if an electron transporting layerand a hole transporting layer is formed adjacent to the light emittinglayer, a compound having triplet energy larger than that of thephosphorescent dopant material should be used also in the electrontransporting layer and the hole transporting layer. Thus, the devicedesign conventionally employed for developing a phosphorescent organicEL device results in the use of a compound having an energy gap largerthan that of a compound for use in a fluorescent organic EL device,thereby increasing the voltage for driving an organic EL device.

A hydrocarbon compound highly resistant to oxidation and reduction,which has been known as a useful compound for a fluorescent device, hasa small energy gap because of a broad distribution of π-electron cloud.Therefore, such a hydrocarbon compound is not suitable for use in aphosphorescent organic EL device and, instead, an organic compoundhaving a heteroatom, such as oxygen and nitrogen, has been selected.However, a phosphorescent organic EL device employing such an organiccompound having a heteroatom has a shorter lifetime as compared with afluorescent organic EL device.

In addition, a phosphorescent dopant material has an extremely longerrelaxation time of triplet excitons as compared with that of its singletexcitons, this largely affecting the device performance. Namely, in theemission from singlet excitons, since the relaxation speed which leadsto emission is high, the diffusion of excitons into a layer adjacent tothe light emitting layer (for example, a hole transporting layer and anelectron transporting layer) is difficult to occur and efficientemission is expected. In contrast, the emission from triplet excitons isa spin-forbidden transition and the relaxation speed is low. Therefore,the diffusion of excitons into adjacent layers occurs easily and thethermal energy deactivation occurs in most compounds other than thespecific phosphorescent compound. Thus, as compared with a fluorescentorganic EL device, it is more important for a phosphorescent organic ELdevice to control the region for recombining electrons and holes.

For the above reasons, the development of a high performancephosphorescent organic EL device requires the selection of materials andthe consideration of device design which are different from those for afluorescent organic EL device.

A carbazole derivative having a high triplet energy known as a holetransporting material has been used as a useful host material ofphosphorescent organic EL device.

Patent Documents 1 and 2 describes to use a compound in which anitrogen-containing heterocyclic group is introduced into a biscarbazoleskeleton which includes two carbazole structures connected to each otherin the light emitting layer of phosphorescent organic EL device as thehost material. The compounds described in Patent Documents 1 and 2 aremolecularly designed to balance the charge transport by introducing anelectron-deficient nitrogen-containing heterocyclic group to a holetransporting carbazole skeleton. However, organic EL devices employingthe compounds described in Patent Documents 1 and 2 have been requiredto improve their lifetime.

Patent Document 3 discloses that the lifetime is prolonged by combinedlyusing two or more kinds of host materials in the light emitting layerand many studies have been made on the combination of host materials.

However, an organic EL device having a further prolonged lifetime hasbeen demanded.

PRIOR ART Patent Documents

-   Patent Document 1: WO2011/132683-   Patent Document 2: WO2011/132684-   Patent Document 3: WO2011/155507

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

An object of the invention is to provide an organic electroluminescencehaving a long lifetime.

Means for Solving Problem

As a results of extensive research for achieving the above object, theinventors have found that the lifetime of organic EL device can befurther increased by using a specific biscarbazole derivative having acyano group as a first host and a compound having both a carbazolestructure and a nitrogen-containing aromatic heteroring as a second hostin a light emitting layer.

The present invention is based on this finding.

The present invention provides:

1. An organic electroluminescence device which comprises a lightemitting layer which is disposed between a cathode and an anode andcomprises a first host material, a second host material and a lightemitting material,

wherein

the first host material is represented by formula (A):

wherein

each of A¹ and A² independently represents a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms or a substituted or unsubstituted heterocyclic group having 5 to30 ring atoms;

A³ represents a substituted or unsubstituted divalent aromatichydrocarbon group having 6 to 30 ring carbon atoms or a substituted orunsubstituted divalent heterocyclic group having 5 to 30 ring atoms;

m represents an integer of 0 to 3;

each of X¹ to X⁸ and Y¹ to Y⁸ independently represents N or CR^(a);

each of R^(a) independently represents a hydrogen atom, a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms, a substituted or unsubstituted heterocyclic group having 5 to 30ring atoms, a substituted or unsubstituted alkyl group having 1 to 30carbon atoms, a substituted or unsubstituted silyl group, a halogenatom, or a cyano group, provided that when two or more R^(a) groupsexist, the R^(a) groups may be the same or different and one of X⁵ to X⁸and one of Y¹ to Y⁴ are bonded to each other via A³; and

the formula (A) satisfies at least one of the following requirements (i)to (v):

(i) at least one of A¹ and A² represents a cyano-substituted aromatichydrocarbon group having 6 to 30 ring carbon atoms or acyano-substituted heterocyclic group having 5 to 30 ring atoms;

(ii) at least one of X¹ to X⁴ and Y⁵ to Y⁸ represents CR^(a), and atleast one of R^(a) in X¹ to X⁴ and Y⁵ to Y⁸ represents acyano-substituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms or a cyano-substituted heterocyclic group having 5 to 30 ringatoms;

(iii) m represents an integer of 1 to 3 and at least one of A³represents a cyano-substituted divalent aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms or a cyano-substituted divalentheterocyclic group having 5 to 30 ring atoms;

(iv) at least one of X⁵ to X⁸ and Y¹ to Y⁴ represents CR^(a), and atleast one of R^(a) in X⁵ to X⁸ and Y¹ to Y⁸ represents acyano-substituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms or a cyano-substituted heterocyclic group having 5 to 30 ringatoms; and

(v) at least one of X¹ to X⁸ and Y¹ to Y⁸ represents C—CN; and

the second host material is represented by formula (1):

wherein

Z¹ represents a ring structure fused to a side a and represented byformula (1-1) or (1-2), and Z² represents a ring structure fused to aside b and represented by formula (1-1) or (1-2), provided that at leastone of Z¹ and Z² is represented by formula (1-1):

in formula (1-1),

a side c is fused to the side a or b of formula (1);

in formula (1-2),

any one of sides d, e and f is fused to the side a or b of formula (1);

in formulae (1-1) and (1-2),

X¹¹ represents a sulfur atom, an oxygen atom, N—R¹⁹, or C(R²⁰)(R²¹);

each of R¹¹ to R²¹ independently represents a hydrogen atom, a heavyhydrogen atom, a halogen atom, a cyano group, a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms, a substituted or unsubstituted heterocyclic group having 5 to 30ring atoms, a substituted or unsubstituted alkyl group having 1 to 30carbon atoms, a substituted or unsubstituted alkenyl group having 2 to30 carbon atoms, a substituted or unsubstituted alkynyl group having 2to 30 carbon atoms, a substituted or unsubstituted alkylsilyl grouphaving 3 to 30 carbon atoms, a substituted or unsubstituted arylsilylgroup having 6 to 30 ring carbon atoms, a substituted or unsubstitutedalkoxy group having 1 to 30 carbon atoms, a substituted or unsubstitutedaralkyl group having 6 to 30 ring carbon atoms, or a substituted orunsubstituted aryloxy group having 6 to 30 ring carbon atoms, providedthat adjacent groups of R¹¹ to R²¹ may be bonded to each other to form aring;

M¹ represent a substituted or unsubstituted nitrogen-containing aromaticheteroring having 5 to 30 ring atoms;

L¹ represents a single bond, a substituted or unsubstituted divalentaromatic hydrocarbon group having 6 to 30 ring carbon atoms, asubstituted or unsubstituted divalent heterocyclic group having 5 to 30ring atoms, a cycloalkylene group having 5 to 30 ring atoms, or a groupin which the preceding groups are directly linked to each other; and

k represents 1 or 2;

2. The organic electroluminescence device according to item 1, whereinthe first host material satisfies at least one of the requirements (i)and (ii);

3. The organic electroluminescence device according to item 1 or 2,wherein A³ of formula (A) represents a substituted or unsubstituteddivalent monocyclic hydrocarbon group having 6 or less ring carbon atomsor a substituted or unsubstituted divalent monocyclic heterocyclic grouphaving 6 or less ring atoms;

4. The organic electroluminescence device according to any one of items1 to 3, wherein the second host material is represented by formula (2):

wherein

Z¹ represents a ring structure fused to the side a and represented byformula (1-1) or (1-2), and Z² represents a ring structure fused to theside b and represented by formula (1-1) or (1-2), provided that at leastone of Z¹ and Z² is represented by formula (1-1);

L¹ is as defined in formula (1);

each of X¹² to X¹⁴ independently represents a nitrogen atom, CH, or acarbon atom bonded to R³¹ or L¹, provided that at least one of X¹² toX¹⁴ represents a nitrogen atom;

each of Y¹¹ to Y¹³ independently represents CH or a carbon atom bondedto R³¹ or L¹;

each of R³¹ independently represents a halogen atom, a cyano group, asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, a substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, a substituted or unsubstituted alkyl grouphaving 1 to 30 carbon atoms, a substituted or unsubstituted alkenylgroup having 2 to 30 carbon atoms, a substituted or unsubstitutedalkynyl group having 2 to 30 carbon atoms, a substituted orunsubstituted alkylsilyl group having 3 to 30 carbon atoms, asubstituted or unsubstituted arylsilyl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted alkoxy group having 1 to 30 carbonatoms, a substituted or unsubstituted aralkyl group having 6 to 30 ringcarbon atoms, or a substituted or unsubstituted aryloxy group having 6to 30 ring carbon atoms;

when two or more R³¹ groups exist, the R³¹ groups may be the same ordifferent and adjacent R³¹ groups may be bonded to each other to form aring;

k represents 1 or 2, and n represents an integer of 0 to 4;

the side c of formula (1-1) is fused to the side a or b of formula (2);and

any one of sides d, e and f of formula (1-2) is fused to the side a or bof formula (2);

5. The organic electroluminescence device according to any one of items1 to 4, wherein the second host material is represented by formula (3):

wherein

L¹ is as defined in formula (1);

each of X¹² to X¹⁴ independently represents a nitrogen atom, CH, or acarbon atom bonded to R³¹ or L¹, provided that at least one of X¹² toX¹⁴ represents a nitrogen atom;

each of Y¹¹ to Y¹³ independently represents CH or a carbon atom bondedto R³¹ or L¹;

each of R³¹ independently represents a halogen atom, a cyano group, asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, a substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, a substituted or unsubstituted alkyl grouphaving 1 to 30 carbon atoms, a substituted or unsubstituted alkenylgroup having 2 to 30 carbon atoms, a substituted or unsubstitutedalkynyl group having 2 to 30 carbon atoms, a substituted orunsubstituted alkylsilyl group having 3 to 30 carbon atoms, asubstituted or unsubstituted arylsilyl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted alkoxy group having 1 to 30 carbonatoms, a substituted or unsubstituted aralkyl group having 6 to 30 ringcarbon atoms, or a substituted or unsubstituted aryloxy group having 6to 30 ring carbon atoms; when two or more R³¹ groups exist, the R³¹groups may be the same or different and adjacent R³¹ groups may bebonded to each other to form a ring;

n represents an integer of 0 to 4;

each of R⁴¹ to R⁴⁸ independently represents a hydrogen atom, a heavyhydrogen atom, a halogen atom, a cyano group, a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms, a substituted or unsubstituted heterocyclic group having 5 to 30ring atoms, a substituted or unsubstituted alkyl group having 1 to 30carbon atoms, a substituted or unsubstituted alkenyl group having 2 to30 carbon atoms, a substituted or unsubstituted alkynyl group having 2to 30 carbon atoms, a substituted or unsubstituted alkylsilyl grouphaving 3 to 30 carbon atoms, a substituted or unsubstituted arylsilylgroup having 6 to 30 ring carbon atoms, a substituted or unsubstitutedalkoxy group having 1 to 30 carbon atoms, a substituted or unsubstitutedaralkyl group having 6 to 30 ring carbon atoms, or a substituted orunsubstituted aryloxy group having 6 to 30 ring carbon atoms; and

adjacent groups of R⁴¹ to R⁴⁸ may be bonded to each other to form aring;

6. The organic electroluminescence device according to any one of items1 to 5, wherein the first host material satisfies only the requirement(i);

7. The organic electroluminescence device according to any one of items1 to 5, wherein the second host material is represented by formula (4):

wherein

L¹ is as defined in formula (1);

each of X¹² to X¹⁴ independently represents a nitrogen atom, CH, or acarbon atom bonded to R³¹ or L¹, provided that at least one of X¹² toX¹⁴ represents a nitrogen atom;

each of Y¹¹ to Y¹³ independently represents CH or a carbon atom bondedto R³¹ or L¹;

each of R³¹ independently represents a halogen atom, a cyano group, asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, a substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, a substituted or unsubstituted alkyl grouphaving 1 to 30 carbon atoms, a substituted or unsubstituted alkenylgroup having 2 to 30 carbon atoms, a substituted or unsubstitutedalkynyl group having 2 to 30 carbon atoms, a substituted orunsubstituted alkylsilyl group having 3 to 30 carbon atoms, asubstituted or unsubstituted arylsilyl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted alkoxy group having 1 to 30 carbonatoms, a substituted or unsubstituted aralkyl group having 6 to 30 ringcarbon atoms, or a substituted or unsubstituted aryloxy group having 6to 30 ring carbon atoms;

when two or more R³¹ groups exist, the R³¹ groups may be the same ordifferent and adjacent R³¹ groups may be bonded to each other to form aring;

n represents an integer of 0 to 4;

each of L² and L³ independently represents a single bond, a substitutedor unsubstituted divalent aromatic hydrocarbon group having 6 to 30 ringcarbon atoms, a substituted or unsubstituted divalent heterocyclic grouphaving 5 to 30 ring atoms, a cycloalkylene group having 5 to 30 ringatoms, or a group in which the preceding groups are directly linked toeach other;

each of R⁵¹ to R⁵⁴ independently represents a halogen atom, a cyanogroup, a substituted or unsubstituted aromatic hydrocarbon group having6 to 30 ring carbon atoms, a substituted or unsubstituted heterocyclicgroup having 5 to 30 ring atoms, a substituted or unsubstituted alkylgroup having 1 to 30 carbon atoms, a substituted or unsubstitutedalkenyl group having 2 to 30 carbon atoms, a substituted orunsubstituted alkynyl group having 2 to 30 carbon atoms, a substitutedor unsubstituted alkylsilyl group having 3 to 30 carbon atoms, asubstituted or unsubstituted arylsilyl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted alkoxy group having 1 to 30 carbonatoms, a substituted or unsubstituted aralkyl group having 6 to 30 ringcarbon atoms, or a substituted or unsubstituted aryloxy group having 6to 30 ring carbon atoms;

when two or more R⁵¹ groups exist, the R⁵¹ groups may be the same ordifferent and adjacent R⁵¹ groups may be bonded to each other to form aring;

when two or more R⁵² groups exist, the R⁵² groups may be the same ordifferent and adjacent R⁵² groups may be bonded to each other to form aring;

when two or more R⁵³ groups exist, the R⁵³ groups may be the same ordifferent and adjacent R⁵³ groups may be bonded to each other to form aring;

when two or more R⁵⁴ groups exist, the R⁵⁴ groups may be the same ordifferent and adjacent R⁵⁴ groups may be bonded to each other to form aring;

M² represents a substituted or unsubstituted aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms or a substituted or unsubstitutedheterocyclic group having 5 to 30 ring atoms; and

each of p and s independently represents an integer of 0 to 4, and eachof q and r independently represents an integer of 0 to 3;

8. The organic electroluminescence device according to any one of items1 to 7, wherein at least one of A¹ and A² represents a cyano-substitutedphenyl group, a cyano-substituted naphthyl group, a cyano-substitutedphenanthryl group, a cyano-substituted dibenzofuranyl group, acyano-substituted dibenzothiophenyl group, a cyano-substituted biphenylgroup, a cyano-substituted terphenyl group, a cyano-substituted9,9-diphenylfluorenyl group, a cyano-substituted9,9′-spirobi[9H-fluorene]-2-yl group, a cyano-substituted9,9′-dimethylfluorenyl group, or a cyano-substituted triphenylenylgroup;

9. The organic electroluminescence device according to any one of items1 to 8, wherein the light emitting material comprises a phosphorescentemitting material selected from ortho metallated complexes of a metalselected from iridium (Ir), osmium (Os), and platinum (Pt); and

10. The organic electroluminescence device according to any one of items1 to 9, wherein a peak of emission wavelength of the phosphorescentemitting material is 490 nm or longer and 700 nm or shorter.

Effect of the Invention

According to the present invention, an organic electroluminescencedevice having a long lifetime is provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view of an example of the organicEL device of the invention.

MODE FOR CARRYING OUT THE INVENTION

The organic electroluminescence device (hereinafter also referred to as“organic EL device”) of the invention comprises a light emitting layerdisposed between a cathode and an anode, wherein the light emittinglayer comprises a first host material represented by the followingformula (A), a second host material represented by the following formula(1), and a light emitting material.

First Host Material

wherein

each of A¹ and A² independently represents a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms or a substituted or unsubstituted heterocyclic group having 5 to30 ring atoms;

A³ represents a substituted or unsubstituted divalent aromatichydrocarbon group having 6 to 30 ring carbon atoms or a substituted orunsubstituted divalent heterocyclic group having 5 to 30 ring atoms

m represents an integer of 0 to 3;

each of X¹ to X⁸ and Y¹ to Y⁸ independently represents N or CRa;

each of R^(a) independently represents a hydrogen atom, a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms, a substituted or unsubstituted heterocyclic group having 5 to 30ring atoms, a substituted or unsubstituted alkyl group having 1 to 30carbon atoms, a substituted or unsubstituted silyl group, a halogenatom, or a cyano group, provided that when two or more R^(a) groupsexist, the R^(a) groups may be the same or different and one of X⁵ to X⁸and one of Y¹ to Y⁴ are bonded to each other via A³; and

the formula (A) satisfies at least one of the flowing requirements (i)to (v);

(i) at least one of A¹ and A² represents a cyano-substituted aromatichydrocarbon group having 6 to 30 ring carbon atoms or acyano-substituted heterocyclic group having 5 to 30 ring atoms;

(ii) at least one of X¹ to X⁴ and Y⁵ to Y⁸ represents CR^(a), and atleast one of R^(a) in X¹ to X⁴ and Y⁵ to Y⁸ represents acyano-substituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms or a cyano-substituted heterocyclic group having 5 to 30 ringatoms;

(iii) m represents an integer of 1 to 3 and at least one of A³represents a cyano-substituted divalent aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms or a cyano-substituted divalentheterocyclic group having 5 to 30 ring atoms;

(iv) at least one of X⁵ to X⁸ and Y¹ to Y⁴ represents CR^(a), and atleast one of R^(a) in X⁵ to X⁸ and Y¹ to Y⁸ represents acyano-substituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms or a cyano-substituted heterocyclic group having 5 to 30 ringatoms; and

(v) at least one of X¹ to X⁸ and Y¹ to Y⁸ represents C—CN.

The cyano-substituted aromatic hydrocarbon group having 6 to 30 ringcarbon atoms and the cyano-substituted heterocyclic group having 5 to 30ring atoms may be further substituted by a group other than the cyanogroup.

The subscript m is preferably 0 to 2 and more preferably 0 or 1. When mis 0, one of X⁵ to X⁸ and one of Y¹ to Y⁴ are bonded to each other via asingle bond.

The aromatic hydrocarbon group having 6 to 30 ring carbon atomsrepresented by A¹, A² and R^(a) may be a non-condensed aromatichydrocarbon group or a condensed aromatic hydrocarbon group. Specificexamples thereof include phenyl group, naphthyl group, phenanthrylgroup, biphenyl group, terphenyl group, quaterphenyl group,fluoranthenyl group, triphenylenyl group, phenanthrenyl group, fluorenylgroup, spirofluorenyl group, 9,9-diphenylfluorenyl group,9,9′-spirobi[9H-fluorene]-2-yl group, 9,9-dimethylfluorenyl group,benzo[c]phenanthrenyl group, benzo[a]triphenylenyl group,naphtho[1,2-c]phenanthrenyl group, naphtho[1,2-a]triphenylenyl group,dibenzo[a,c]triphenylenyl group, and benzo[b]fluoranthenyl group, withphenyl group, naphthyl group, biphenyl group, terphenyl group,phenanthryl group, triphenylenyl group, fluorenyl group,spirobifluorenyl group, and fluoranthenyl group being preferred, andphenyl group, 1-naphthyl group, 2-naphthyl group, biphenyl-2-yl group,biphenyl-3-yl group, biphenyl-4-yl group, phenanthrene-9-yl group,phenanthrene-3-yl group, phenanthrene-2-yl group, triphenylene-2-ylgroup, 9,9-dimethylfluorene-2-yl group, fluoranthene-3-yl group beingmore preferred.

Examples of the divalent aromatic hydrocarbon group having 6 to 30 ringcarbon atoms represented by A³ include divalent residues of the abovearomatic hydrocarbon groups having 6 to 30 ring carbon atoms.

The heterocyclic group having 5 to 30 ring atoms represented by A¹, A²and R^(a) may be a non-condensed heterocyclic group or a condensedheterocyclic group. Specific examples thereof include the residues ofpyrrole ring, isoindole ring, benzofuran ring, isobenzofuran ring,dibenzothiophene ring, isoquinoline ring, quinoxaline ring,phenanthridine ring, phenanthroline ring, pyridine ring, pyrazine ring,pyrimidine ring, pyridazine ring, triazine ring, indole ring, quinolinering, acridine ring, pyrrolidine ring, dioxane ring, piperidine ring,morpholine ring, piperazine ring, carbazole ring, furan ring, thiophenering, oxazole ring, oxadiazole ring, benzoxazole ring, thiazole ring,thiadiazole ring, benzothiazole ring, triazole ring, imidazole ring,benzimidazole ring, pyran ring, dibenzofuran ring, andbenzo[c]dibenzofuran ring, and the residues of derivatives of theserings, with the residues of dibenzofuran ring, carbazole ring,dibenzothiophene ring, and derivatives of these rings being preferred,and the residues of dibenzofuran-2-yl group, dibenzofuran-4-yl group,9-phenylcarbazole-3-yl group, 9-phenylcarbazole-2-yl group,dibenzothiophene-2-yl group, and dibenzothiophene-4-yl group being morepreferred.

Examples of the divalent heterocyclic group having 5 to 30 ring atomsrepresented by A³ include divalent residues of the above heterocyclicgroup having 5 to 30 ring atoms.

Examples of the alkyl group having 1 to 30 carbon atoms represented byR^(a) include methyl group, ethyl group, n-propyl group, isopropylgroup, n-butyl group, s-butyl group, isobutyl group, t-butyl group,n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonylgroup, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecylgroup, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group,n-heptadecyl group, n-octadecyl group, neopentyl group, 1-methylpentylgroup, cyclopropyl group, cyclobutyl group, cyclopentyl group,cyclohexyl group, cyclooctyl group, and adamantyl group, with methylgroup, ethyl group, n-propyl group, isopropyl group, n-butyl group,s-butyl group, isobutyl group, t-butyl group, cyclopentyl group, andcyclohexyl group being preferred.

Examples of the substituted or unsubstituted silyl group represented byR^(a) include trimethylsilyl group, triethylsilyl group, tributylsilylgroup, dimethylethylsilyl group, t-butyldimethylsilyl group,vinyldimethylsilyl group, propyldimethylsilyl group,dimethylisopropylsilyl group, dimethylpropylsilyl group,dimethylbutylsilyl group, dimethyltertiarybutylsilyl group,diethylisopropylsilyl group, phenyldimethylsilyl group,diphenylmethylsilyl group, diphenyltertiarybutylsilyl group, andtriphenylsilyl group, with trimethylsilyl group, triethylsilyl group,t-butyldimethylsilyl group, vinyldimethylsilyl group, andpropyldimethylsilyl group being preferred.

Examples of the halogen atom represented by R^(a) include fluorine,chlorine, bromine, and iodine, with fluorine being preferred.

Also preferred as R^(a) is a hydrogen atom or a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms.

Examples of the optional substituent indicated by “substituted orunsubstituted” and “may be substituted” referred to above or hereinafterinclude a halogen atom (fluorine, chlorine, bromine, iodine), a cyanogroup, an alkyl group having 1 to 20, preferably 1 to 6 carbon atoms, acycloalkyl group having 3 to 20, preferably 5 to 12 carbon atoms, analkoxyl group having 1 to 20, preferably 1 to 5 carbon atoms, ahaloalkyl group having 1 to 20, preferably 1 to 5 carbon atoms, ahaloalkoxyl group having 1 to 20, preferably 1 to 5 carbon atoms, analkylsilyl group having 1 to 10, preferably 1 to 5 carbon atoms, anaromatic hydrocarbon group having 6 to 30, preferably 6 to 18 ringcarbon atoms, an aryloxy group having 6 to 30, preferably 6 to 18 ringcarbon atoms, an arylsilyl group having 6 to 30, preferably 6 to 18carbon atoms, an aralkyl group having 7 to 30, preferably 7 to 20 carbonatoms, and a heteroaryl group having 5 to 30, preferably 5 to 18 ringatoms.

Examples of the optional alkyl group having 1 to 20 carbon atoms includemethyl group, ethyl group, n-propyl group, isopropyl group, n-butylgroup, s-butyl group, isobutyl group, t-butyl group, n-pentyl group,n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decylgroup, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecylgroup, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group,n-octadecyl group, neopentyl group, and 1-methylpentyl group.

Examples of the optional cycloalkyl group having 3 to 20 carbon atomsinclude cyclopropyl group, cyclobutyl group, cyclopentyl group,cyclohexyl group, cyclooctyl group, and adamantyl group.

Examples of the optional alkoxyl group having 1 to 20 carbon atomsinclude those having an alkyl portion selected from the alkyl groupsmentioned above.

Examples of the optional haloalkyl group having 1 to 20 carbon atomsinclude the alkyl groups mentioned above wherein the hydrogen atomsthereof are partly or entirely substituted by halogen atoms.

Examples of the optional haloalkoxyl group having 1 to 20 carbon atomsinclude the alkoxyl group mentioned above wherein the hydrogen atomsthereof are partly or entirely substituted by halogen atoms.

Examples of the optional alkylsilyl group having 1 to 10 carbon atomsinclude trimethylsilyl group, triethylsilyl group, tributylsilyl group,dimethylethylsilyl group, t-butyldimethylsilyl group, vinyldimethylsilylgroup, propyldimethylsilyl group, dimethylisopropylsilyl group,dimethylpropylsilyl group, dimethylbutylsilyl group,dimethyltertiarybutylsilyl group, and diethylisopropylsilyl group.

Examples of the optional aromatic hydrocarbon group having 6 to 30 ringcarbon atoms include those selected from the aromatic hydrocarbon groupsmentioned above with respect to A¹, A² and R^(a).

Examples of the optional aryloxy group having 6 to 30 ring carbon atomsinclude those having an aryl portion selected from the aromatichydrocarbon groups mentioned above.

Examples of the optional arylsilyl group having 6 to 30 carbon atomsinclude phenyldimethylsilyl group, diphenylmethylsilyl group,diphenyltertiarybutylsilyl group, and triphenylsilyl group.

Examples of the optional aralkyl group having 7 to 30 carbon atomsinclude benzyl group, 2-phenylpropane-2-yl group, 1-phenylethyl group,2-phenylethyl group, 1-phenylisopropyl group, 2-phenylisopropyl group,phenyl-t-butyl group, α-naphthylmethyl group, 1-α-naphthylethyl group,2-α-naphthylethyl group, 1-α-naphthylisopropyl group,2-α-naphthylisopropyl group, β-naphthylmethyl group, 1-β-naphthylethylgroup, 2-β-naphthylethyl group, 1-β-naphthylisopropyl group,2-β-naphthylisopropyl group, 1-pyrrolylmethyl group, 2-(1-pyrrolyl)ethylgroup, p-methylbenzyl group, m-methylbenzyl group, o-methylbenzyl group,p-chlorobenzyl group, m-chlorobenzyl group, o-chlorobenzyl group,p-bromobenzyl group, m-bromobenzyl group, o-bromobenzyl group,p-iodobenzyl group, m-iodobenzyl group, o-iodobenzyl group,p-hydroxybenzyl group, m-hydroxybenzyl group, o-hydroxybenzyl group,p-aminobenzyl group, m-aminobenzyl group, o-aminobenzyl group,p-nitrobenzyl group, m-nitrobenzyl group, o-nitrobenzyl group,p-cyanobenzyl group, m-cyanobenzyl group, o-cyanobenzyl group,1-hydroxy-2-phenylisopropyl group, and 1-chloro-2-phenylisopropyl group.

Examples of the optional heteroaryl group having 5 to 30 ring atomsinclude those selected from the heterocyclic groups mentioned above withrespect to A¹, A² and R^(a).

The optional substituent is preferably fluorine atom, cyano group, thealkyl group having 1 to 20 carbon atoms, the aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms, and the heteroaryl group having 5 to30 ring atoms, more preferably fluorine atom, phenyl group, naphthylgroup, biphenyl group, terphenyl group, phenanthryl group, triphenylenylgroup, fluorenyl group, spirobifluorenyl group, fluoranthenyl group,residues of dibenzofuran ring, carbazole ring, dibenzothiophene ring,and their derivatives, methyl group, ethyl group, n-propyl group,isopropyl group, n-butyl group, s-butyl group, isobutyl group, t-butylgroup, cyclopentyl group, and cyclohexyl group.

The optional substituent mentioned above may be further substituted bythe optional group mentioned above.

The “carbon number of a to b” in the expression of “substituted orunsubstituted X group having carbon number of a to b” is the carbonnumber of the unsubstituted X group and does not include the carbon atomof the optional substituent.

The hydrogen atom referred to herein includes isotopes different fromneutron numbers, i.e., light hydrogen (protium), heavy hydrogen(deuterium) and tritium.

In the first host material represented by formula (A), the groupsrepresented by formulae (a) and (b) are bonded to each other via-(A³)_(m)- at one of X⁵ to X⁸ and one of Y¹ to Y⁴. Specific examples ofthe bonding manner between formulae (a) and (b) are represented byX⁶-(A³)_(m)-Y³, X⁶-(A³)_(m)-Y², X⁶-(A³)_(m)-Y⁴, X⁶-(A³)_(m)-Y¹,X⁷-(A³)_(m)-Y³, X⁵-(A³)_(m)-Y³, X⁸-(A³)_(m)-Y³, X⁷-(A³)_(m)-Y²,X⁷-(A³)_(m)-Y⁴, X⁷-(A³)_(m)-Y¹, X⁵-(A³)_(m)-Y², X⁸-(A³)_(m)-Y²,X⁸-(A³)_(m)-Y⁴, X⁸-(A³)_(m)-Y¹, X⁵-(A³)_(m)-Y¹, and X⁵-(A³)_(m)-Y⁴.

In preferred embodiments of the first host material represented byformula (A), the bonding manner between formulae (a) and (b) arerepresented by X⁶-(A³)_(m)-Y³, X⁶-(A³)_(m)-Y², or X⁷-(A³)_(m)-Y³, namelythe material for organic electroluminescence device is preferablyrepresented by formula (II), (III), or (IV):

wherein X¹ to X⁸, Y¹ to Y⁸, A¹ to A³, and m are the same as X¹ to X⁸, Y¹to Y⁸, A¹ to A³, m in formula (A), and each of formulae (II), (III), and(IV) satisfies at least one of the requirements (i) to (v) as specifiedin the definition of formula (A).

The first host material represented by formula (A) satisfies at leastone of the requirements (i) to (v), namely, the first host material is acyano group-introduced biscarbazole derivative having a grouprepresented by formula (a) and a group represented by formula (b) whichare linked to each otter.

Since an electron injecting/transporting cyano group is introduced, thefirst host material has an improved hole resistance. Therefore, theorganic EL device comprising the first host material having a cyanogroup exhibits a prolonged lifetime as compared with a known organic ELdevice comprising a host material having no cyano group.

A³ of formula (A) preferably represents a single bond, a substituted orunsubstituted divalent monocyclic hydrocarbon group having 6 or lessring carbon atoms, or a substituted or unsubstituted divalent monocyclicheterocyclic group having 6 or less ring atoms.

Examples of the monocyclic hydrocarbon group having 6 or less ringcarbon atoms represented by A³ include phenylene group, cyclopentenylenegroup, cyclopentadienylene group, cyclohexylene group, andcyclopentylene group, with phenylene group being preferred.

Examples of the monocyclic heterocyclic group having 6 or less ringatoms represented by A³ include pyrrolylene group, pyrazinylene group,pyridinylene group, furylene group, and thiophenylene group.

In a preferred embodiment of formulae (A), (II), (III), and (IV), m is 0and one of X⁵ to X⁸ and one of Y¹ to Y⁴ are bonded to each other via asingle bond; or A³ represents the substituted or unsubstitutedmonocyclic hydrocarbon group having 6 or less ring carbon atoms or thesubstituted or unsubstituted monocyclic heterocyclic group having 6 orless ring atoms. In such a preferred embodiment, the distortion of thering (for example, carbazole ring) represented by formula (a) or (b) isminimized to make it easy to retain the conjugation of π-electrons. Thisallows HOMO (highest occupied molecular orbital) to extend throughoutthe whole carbazole skeleton, thereby to retain the holeinjecting/transporting ability of the carbazole skeleton. In morepreferred embodiment, m is 0 and one of X⁵ to X⁸ and one of Y¹ to Y⁴ arebonded to each other via a single bond; or A³ represents a substitutedor unsubstituted phenylene group.

The first host material satisfies preferably at least one of therequirements (i) and (ii);

(i) at least one of A¹ and A² represents a cyano-substituted aromatichydrocarbon group having 6 to 30 ring carbon atoms or acyano-substituted heterocyclic group having 5 to 30 ring atoms; and

(ii) at least one of X¹ to X⁴ and Y⁵ to Y⁸ represents CR^(a), and atleast one of R^(a) in X¹ to X⁴ and Y⁵ to Y⁸ represents acyano-substituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms or a cyano-substituted heterocyclic group having 5 to 30 ringatoms.

Namely, the first host material is preferably any one of the compounds;

-   (1) satisfying the requirement (i), but not satisfying the    requirements (ii) to (v);-   (2) satisfying the requirement (ii), but not satisfying the    requirements (i) and (iii) to (v); and-   (3) satisfying both the requirements (i) and (ii), but not    satisfying the requirements (iii) to (v).

The first host material satisfying the requirement (i) and/or (ii) has astructure wherein the cyano group-containing aromatic hydrocarbon groupor the cyano group-containing heterocyclic group is introduced to theterminal end of the central skeleton comprising the groups representedby formulae (a) and (b).

The central skeleton comprising the groups represented by formulae (a)and (b) acts as a hole injecting/transporting unit, and each of thecyano group-containing aromatic hydrocarbon group and the cyanogroup-containing heterocyclic group acts as an electroninjecting/transporting unit. Since the first host material satisfyingthe requirement (i) or (ii) has the cyano group-containing group whichacts as an electron injecting/transporting unit outside the centralskeleton, the distribution of the electron cloud of HOMO (highestoccupied molecular orbital) is retained within the central skeleton, tomaintain the hole injecting/transporting ability of the central skeletongood while retaining the electron injecting/transporting ability of thecyano group-containing group. Therefore, the carrier balance in themolecule of the first host material satisfying the requirement (i) or(ii) is good to realize an organic EL device with excellent emissionefficiency.

Thus, the organic EL device having a light emitting layer comprising thefirst host material satisfying at least one of the requirements (i) and(ii) and the second host material represented by formula (1) alsoexhibits excellent emission efficiency in addition to a prolongedlifetime.

When the first host material satisfies the requirement (i), at least oneof A¹ and A² is preferably a cyano-substituted phenyl group, acyano-substituted naphthyl group, a cyano-substituted phenanthryl group,a cyano-substituted dibenzofuranyl group, a cyano-substituteddibenzothiophenyl group, a cyano-substituted biphenyl group, acyano-substituted terphenyl group, a cyano-substituted9,9-diphenylfluorenyl group, a cyano-substituted9,9′-spirobi[9H-fluorene]-2-yl group, a cyano-substituted9,9′-dimethylfluorenyl group, or a cyano-substituted triphenylenylgroup, and more preferably 3′-cyanobiphenyl-2-yl group,3′-cyanobiphenyl-3-yl group, 3′-cyanobiphenyl-4-yl group,4′-cyanobiphenyl-3-yl group, 4′-cyanobiphenyl-4-yl group,4′-cyanobiphenyl-2-yl group, 6-cyanonaphthalene-2-yl group,4-cyanonaphthalene-1-yl group, 7-cyanonaphthalene-2-yl group,8-cyanodibenzofuran-2-yl group, 6-cyanodibenzofuran-4-yl group,8-cyanodibenzothiophene-2-yl group, 6-cyanodibenzothiophene-4-yl group,7-cyano-9-phenylcarbazole-2-yl group, 6-cyano-9-phenylcarbazole-3-ylgroup, 7-cyano-9,9-dimethylfluorene-2-yl group, or7-cyanotriphenylene-2-yl group.

The first host material wherein A¹ is substituted by a cyano group andA² is not substituted by a cyano group is preferred. In this case, thefirst host material which does not satisfy the requirement (ii) is morepreferred.

When the first host material satisfies the requirement (ii), at leastone of X¹ to X⁴ and Y⁵ to Y⁸ is preferably CR^(a), and one of R^(a) inX¹ to X⁴ and Y⁵ to Y⁸ is preferably a cyano-substituted phenyl group, acyano-substituted naphthyl group, a cyano-substituted phenanthryl group,a cyano-substituted dibenzofuranyl group, a cyano-substituteddibenzothiophenyl group, a cyano-substituted biphenyl group, acyano-substituted terphenyl group, a cyano-substituted9,9-diphenylfluorenyl group, a cyano-substituted9,9′-spirobi[9H-fluorene]-2-yl group, a cyano-substituted9,9′-dimethylfluorenyl group, or a cyano-substituted triphenylenylgroup, and more preferably 3′-cyanobiphenyl-2-yl group,3′-cyanobiphenyl-3-yl group, 3′-cyanobiphenyl-4-yl group,4′-cyanobiphenyl-3-yl group, 4′-cyanobiphenyl-4-yl group,4′-cyanobiphenyl-2-yl group, 6-cyanonaphthalene-2-yl group,4-cyanonaphthalene-1-yl group, 7-cyanonaphthalene-2-yl group,8-cyanodibenzofuran-2-yl group, 6-cyanodibenzofuran-4-yl group,8-cyanodibenzothiophene-2-yl group, 6-cyanodibenzothiophene-4-yl group,7-cyano-9-phenylcarbazole-2-yl group, 6-cyano-9-phenylcarbazole-3-ylgroup, 7-cyano-9,9-dimethylfluorene-2-yl group, or7-cyanotriphenylene-2-yl group.

It is preferred for the first host material to satisfy the requirement(ii), but not satisfy the requirement (i).

In formulae (A) and (II) to (IV), A¹ and A² are preferably differentfrom each other, and more preferably, A¹ is substituted by a cyano groupbut A² is not substituted by a cyano group. Namely, the first hostmaterial is preferably structurally asymmetric. If being asymmetric, thecrystallinity and non-crystallinity are good. This enhances the qualityof the films of an organic EL device employing the first host material,thereby achieving high performance, for example, organic EL properties,such as current efficiency.

The production method of the first host material is not particularlylimited and it is produced according to a known method, for example, bya coupling reaction of a carbazole derivative and an aromatichalogenated compound in the presence of a copper catalyst described inTetrahedron 40 (1984) 1435 to 1456 or a palladium catalyst described inJournal of American Chemical Society 123 (2001) 7727 to 7729.

Specific examples of the first host material are shown below, althoughnot limited thereto.

Second Host Material

The second host material which is used in the light emitting layer of anembodiment of organic EL device is represented by formula (1). Thelifetime of an organic EL device is increased by combinedly using thefirst host material represented by formula (A) and the second hostmaterial represented by formula (1) in the light emitting layer.

wherein

Z¹ represents a ring structure fused to the side a and represented byformula (1-1) or (1-2), and Z² represents a ring structure fused to theside b and represented by formula (1-1) or (1-2), provided that at leastone of Z¹ and Z² is represented by formula (1-1);

M¹ represent a substituted or unsubstituted nitrogen-containing aromaticheteroring having 5 to 30 ring atoms;

L¹ represents a single bond, a substituted or unsubstituted divalentaromatic hydrocarbon group having 6 to 30 ring carbon atoms, asubstituted or unsubstituted divalent heterocyclic group having 5 to 30ring atoms, a cycloalkylene group having 5 to 30 ring atoms, or a groupin which the preceding groups are directly linked to each other; and

k represents 1 or 2.

In formula (1-1), a side c is fused to the side a or b of formula (1).

In formula (1-2), any one of sides d, e and f is fused to the side a orb of formula (1).

In formulae (1-1) and (1-2),

X¹¹ represents a sulfur atom, an oxygen atom, N—R¹⁹, or C(R²⁰)(R²¹); and

each of R¹¹ to R²¹ independently represents a hydrogen atom, a heavyhydrogen atom, a halogen atom, a cyano group, a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms, a substituted or unsubstituted heterocyclic group having 5 to 30ring atoms, a substituted or unsubstituted alkyl group having 1 to 30carbon atoms, a substituted or unsubstituted alkenyl group having 2 to30 carbon atoms, a substituted or unsubstituted alkynyl group having 2to 30 carbon atoms, a substituted or unsubstituted alkylsilyl grouphaving 3 to 30 carbon atoms, a substituted or unsubstituted arylsilylgroup having 6 to 30 ring carbon atoms, a substituted or unsubstitutedalkoxy group having 1 to 30 carbon atoms, a substituted or unsubstitutedaralkyl group having 6 to 30 ring carbon atoms, or a substituted orunsubstituted aryloxy group having 6 to 30 ring carbon atoms, providedthat adjacent groups of R¹¹ to R²¹ may be bonded to each other to form aring.

The nitrogen-containing aromatic heteroring represented by M¹ of formula(1) includes an azine rings

Examples of the nitrogen-containing aromatic heteroring includepyridine, pyrimidine, pyrazine, triazine, aziridine, azaindolizine,indolizine, imidazole, indole, isoindole, indazole, purine, pteridine,β-carboline, naphthyridine, quinoxaline, terpyridine, bipyridine,acridine, phenanthroline, phenazine, and imidazopyridine, with pyridine,pyrimidine, and triazine being particularly preferred. The formula (1)is preferably represented by formula (2):

wherein

Z¹ represents a ring structure fused to the side a and represented byformula (1-1) or (1-2), and Z² represents a ring structure fused to theside b and represented by formula (1-1) or (1-2), provided that at leastone of Z¹ and Z² is represented by formula (1-1);

L¹ is as defined in formula (1);

each of X¹² to X¹⁴ independently represents a nitrogen atom, CH, or acarbon atom bonded to R³¹ or L¹, provided that at least one of X¹² toX¹⁴ represents a nitrogen atom;

each of Y¹¹ to Y¹³ independently represents CH or a carbon atom bondedto R³¹ or L¹;

each of R³¹ independently represents a halogen atom, a cyano group, asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, a substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, a substituted or unsubstituted alkyl grouphaving 1 to 30 carbon atoms, a substituted or unsubstituted alkenylgroup having 2 to 30 carbon atoms, a substituted or unsubstitutedalkynyl group having 2 to 30 carbon atoms, a substituted orunsubstituted alkylsilyl group having 3 to 30 carbon atoms, asubstituted or unsubstituted arylsilyl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted alkoxy group having 1 to 30 carbonatoms, a substituted or unsubstituted aralkyl group having 6 to 30 ringcarbon atoms, or a substituted or unsubstituted aryloxy group having 6to 30 ring carbon atoms;

when two or more R³¹ groups exist, the R³¹ groups may be the same ordifferent and adjacent R³¹ groups may be bonded to each other to form aring;

k represents 1 or 2, and n represents an integer of 0 to 4;

the side c of formula (1-1) is fused to the side a or b of formula (2);and

any one of sides d, e and f of formula (1-2) is fused to the side a or bof formula (2).

Examples of the compound wherein the ring represented by formula (1-1)or (1-2) is fused to the side a or b of formula (2) are shown below.

The compound represented by formula (1) or (2) is more preferablyrepresented by formula (3) and particularly preferably represented byformula (4).

In formula (3),

L¹ is as defined in formula (1);

each of X¹² to X¹⁴ independently represents a nitrogen atom, CH, or acarbon atom bonded to R³¹ or L¹, provided that at least one of X¹² toX¹⁴ represents a nitrogen atom;

each of Y¹¹ to Y¹³ independently represents CH or a carbon atom bondedto R³¹ or L¹;

each of R³¹ independently represents a halogen atom, a cyano group, asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, a substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, a substituted or unsubstituted alkyl grouphaving 1 to 30 carbon atoms, a substituted or unsubstituted alkenylgroup having 2 to 30 carbon atoms, a substituted or unsubstitutedalkynyl group having 2 to 30 carbon atoms, a substituted orunsubstituted alkylsilyl group having 3 to 30 carbon atoms, asubstituted or unsubstituted arylsilyl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted alkoxy group having 1 to 30 carbonatoms, a substituted or unsubstituted aralkyl group having 6 to 30 ringcarbon atoms, or a substituted or unsubstituted aryloxy group having 6to 30 ring carbon atoms;

when two or more R³¹ groups exist, the R³¹ groups may be the same ordifferent and adjacent R³¹ groups may be bonded to each other to form aring;

n represents an integer of 0 to 4;

each of R⁴¹ to R⁴⁸ independently represents a hydrogen atom, a heavyhydrogen atom, a halogen atom, a cyano group, a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms, a substituted or unsubstituted heterocyclic group having 5 to 30ring atoms, a substituted or unsubstituted alkyl group having 1 to 30carbon atoms, a substituted or unsubstituted alkenyl group having 2 to30 carbon atoms, a substituted or unsubstituted alkynyl group having 2to 30 carbon atoms, a substituted or unsubstituted alkylsilyl grouphaving 3 to 30 carbon atoms, a substituted or unsubstituted arylsilylgroup having 6 to 30 ring carbon atoms, a substituted or unsubstitutedalkoxy group having 1 to 30 carbon atoms, a substituted or unsubstitutedaralkyl group having 6 to 30 ring carbon atoms, or a substituted orunsubstituted aryloxy group having 6 to 30 ring carbon atoms; and

adjacent groups of R⁴¹ to R⁴⁸ may be bonded to each other to form aring.

In formula (4),

L¹ is as defined in formula (1);

each of X¹² to X¹⁴ independently represents a nitrogen atom, CH, or acarbon atom bonded to R³¹ or L¹, provided that at least one of X¹² toX¹⁴ represents a nitrogen atom;

each of Y¹¹ to Y¹³ independently represents CH or a carbon atom bondedto R³¹ or L¹;

each of R³¹ independently represents a halogen atom, a cyano group, asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, a substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, a substituted or unsubstituted alkyl grouphaving 1 to 30 carbon atoms, a substituted or unsubstituted alkenylgroup having 2 to 30 carbon atoms, a substituted or unsubstitutedalkynyl group having 2 to 30 carbon atoms, a substituted orunsubstituted alkylsilyl group having 3 to 30 carbon atoms, asubstituted or unsubstituted arylsilyl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted alkoxy group having 1 to 30 carbonatoms, a substituted or unsubstituted aralkyl group having 6 to 30 ringcarbon atoms, or a substituted or unsubstituted aryloxy group having 6to 30 ring carbon atoms;

adjacent R³¹ groups may be bonded to each other to form a ring;

n represents an integer of 0 to 4;

each of L² and L³ independently represents a single bond, a substitutedor unsubstituted divalent aromatic hydrocarbon group having 6 to 30 ringcarbon atoms, a substituted or unsubstituted divalent heterocyclic grouphaving 5 to 30 ring atoms, a cycloalkylene group having 5 to 30 ringatoms, or a group in which the preceding groups are directly linked toeach other;

each of R⁵¹ to R⁵⁴ independently represents a halogen atom, a cyanogroup, a substituted or unsubstituted aromatic hydrocarbon group having6 to 30 ring carbon atoms, a substituted or unsubstituted heterocyclicgroup having 5 to 30 ring atoms, a substituted or unsubstituted alkylgroup having 1 to 30 carbon atoms, a substituted or unsubstitutedalkenyl group having 2 to 30 carbon atoms, a substituted orunsubstituted alkynyl group having 2 to 30 carbon atoms, a substitutedor unsubstituted alkylsilyl group having 3 to 30 carbon atoms, asubstituted or unsubstituted arylsilyl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted alkoxy group having 1 to 30 carbonatoms, a substituted or unsubstituted aralkyl group having 6 to 30 ringcarbon atoms, or a substituted or unsubstituted aryloxy group having 6to 30 ring carbon atoms;

when two or more R⁵¹ groups exist, the R⁵¹ groups may be the same ordifferent and adjacent R⁵¹ groups may be bonded to each other to form aring;

when two or more R⁵² groups exist, the R⁵² groups may be the same ordifferent and adjacent R⁵² groups may be bonded to each other to form aring;

when two or more R⁵³ groups exist, the R⁵³ groups may be the same ordifferent and adjacent R⁵³ groups may be bonded to each other to form aring;

when two or more R⁵⁴ groups exist, the R⁵⁴ groups may be the same ordifferent and adjacent R⁵⁴ groups may be bonded to each other to form aring;

M² represents a substituted or unsubstituted aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms or a substituted or unsubstitutedheterocyclic group having 5 to 30 ring atoms; and

each of p and s independently represents an integer of 0 to 4, and eachof q and r independently represents an integer of 0 to 3.

In formulae (1) to (4), (1-1), and (1-2), the groups represented by Rhto R²¹, R³¹, R⁴¹ to R⁴⁸, and R⁵¹ to R⁵⁴ are as defined above withrespect to formula (A).

Examples of the divalent aromatic hydrocarbon group having 6 to 30 ringcarbon atoms and the divalent heterocyclic group having 5 to 30 ringatoms represented by L¹ to L³ of formulae (1) to (4) includes divalentresidues of the corresponding groups described above with respect toformula (A).

Examples of the compounds represented by any of formulae (1) to (4) areshown below. In the following structural formulae, the bond notterminated with a chemical symbol or structure (for example, CN andbenzene ring) denotes a methyl group.

Organic EL Device

The organic EL device of the invention may include a hole transportinglayer, a light emitting layer, a space layer, and a blocking layer. Eachof these layers may contain a compound similar to the first hostmaterial and the second host material.

The light emitting material used in the light emitting layer may includea fluorescent emitting material and a phosphorescent emitting material,with the phosphorescent emitting material being preferred.

The organic EL device of the invention may be any of a single coloremitting device of fluorescent or phosphorescent type, a white-emittingdevice of fluorescent-phosphorescent hybrid type, an emitting device ofa simple type having a single emission unit, and an emitting device of atandem type having two or more emission units, with the phosphorescentdevice being preferred. The “emission unit” referred to herein is thesmallest unit for emitting light by the recombination of injected holesand injected electrons, which comprises one or more organic layerswherein at least one layer is a light emitting layer.

Representative device structures of the simple-type organic EL deviceare shown below.

-   (1) Anode/Emission Unit/Cathode

The emission unit may be a laminate comprising two or more layersselected from a phosphorescent light emitting layer and a fluorescentlight emitting layer. A space layer may be disposed between the lightemitting layers to prevent the diffusion of excitons generated in thephosphorescent light emitting layer into the fluorescent light emittinglayer. Representative layered structures of the emission unit are shownbelow.

-   (a) hole transporting layer/light emitting layer (/electron    transporting layer);-   (b) hole transporting layer/first phosphorescent light emitting    layer/second phosphorescent light emitting layer (/electron    transporting layer);-   (c) hole transporting layer/phosphorescent light emitting    layer/space layer/fluorescent light emitting layer (/electron    transporting layer);-   (d) hole transporting layer/first phosphorescent light emitting    layer/second phosphorescent light emitting layer/space    layer/fluorescent light emitting layer (/electron transporting    layer);-   (e) hole transporting layer/first phosphorescent light emitting    layer/space layer/second phosphorescent light emitting layer/space    layer/fluorescent light emitting layer (/electron transporting    layer);-   (f) hole transporting layer/phosphorescent light emitting    layer/space layer/first fluorescent light emitting layer/second    fluorescent light emitting layer (/electron transporting layer);-   (g) hole transporting layer/electron blocking layer/light emitting    layer (/electron transporting layer);-   (h) hole transporting layer/light emitting layer/hole blocking layer    (/electron transporting layer); and-   (i) hole transporting layer/fluorescent light emitting layer/triplet    blocking layer (/electron transporting layer).

The emission color of the phosphorescent light emitting layer and thatof the fluorescent light emitting layer may be different. For example,the layered structure of the laminated light emitting layer (d) may behole transporting layer/first phosphorescent light emitting layer (redemission)/second phosphorescent light emitting layer (greenemission)/space layer/fluorescent light emitting layer (blueemission)/electron transporting layer.

An electron blocking layer may be disposed between the light emittinglayer and the hole transporting layer or between the light emittinglayer and the space layer, if necessary. Also, a hole blocking layer maybe disposed between the light emitting layer and the electrontransporting layer, if necessary. With such a electron blocking layer ora hole blocking layer, electrons and holes are confined in the lightemitting layer to increase the degree of charge recombination in thelight emitting layer, thereby improving the emission efficiency.

Representative device structure of the tandem-type organic EL device isshown below.

-   (2) Anode/First Emission Unit/Intermediate Layer/Second Emission    Unit/Cathode

The layered structure of the first emission unit and the second emissionunit may be selected from those described above with respect to theemission unit.

Generally, the intermediate layer is also called an intermediateelectrode, an intermediate conductive layer, a charge generation layer,an electron withdrawing layer, a connecting layer, or an intermediateinsulating layer. The intermediate layer may be formed by knownmaterials so as to supply electrons to the first emission unit and holesto the second emission unit.

A schematic structure of an example of the organic EL device of theinvention is shown in FIG. 1 wherein the organic EL device 1 isconstructed by a substrate 2, an anode 3, a cathode 4, and an emissionunit 10 disposed between the anode 3 and the cathode 4. The emissionunit 10 includes a light emitting layer 5 which comprises at least onelayer containing the first host compound, the second host compound, andthe light emitting material. A hole injecting/transporting layer 6, etc.may be disposed between the light emitting layer 5 and the anode 3, andan electron injecting/transporting layer 7, etc. may be disposed betweenthe light emitting layer 5 and the cathode 4. An electron blocking layermay be disposed on the anode 3 side of the light emitting layer 5, and ahole blocking layer may be disposed on the cathode 4 side of the lightemitting layer 5. With these blocking layers, electrons and holes areconfined in the light emitting layer 5 to increase the degree of excitongeneration in the light emitting layer 5.

In the present invention, the host is referred to as a fluorescent hostwhen combinedly used with a fluorescent dopant and as a phosphorescenthost when combinedly used with a phosphorescent dopant. Therefore, thefluorescent host and the phosphorescent host are not distinguished fromeach other merely by the difference in their molecular structures.Namely, the term “phosphorescent host” means a material for constitutinga phosphorescent emitting layer containing a phosphorescent dopant anddoes not mean that the material is not usable as a material forconstituting a fluorescent emitting layer. The same also applies to thefluorescent host.

Substrate

The organic EL device of the invention is formed on a light-transmissivesubstrate. The light-transmissive substrate serves as a support for theorganic EL device and preferably a flat substrate having a transmittanceof 50% or more to 400 to 700 nm visible light. Examples of the substrateinclude a glass plate and a polymer plate. The glass plate may include aplate made of soda-lime glass, barium-strontium-containing glass, leadglass, aluminosilicate glass, borosilicate glass, barium borosilicateglass, or quartz. The polymer plate may include a plate made ofpolycarbonate, acryl, polyethylene terephthalate, polyether sulfide, orpolysulfone.

Anode

The anode of the organic EL device injects holes to the holetransporting layer or the light emitting layer, and an anode having awork function of 4.5 eV or more is effective. Examples of material foranode include indium tin oxide alloy (ITO), tin oxide (NESA), indiumzinc oxide alloy, gold, silver, platinum, and cupper. The anode isformed by making the electrode material into a thin film by a method,such as a vapor deposition method or a sputtering method. When gettingthe light emitted from the light emitting layer through the anode, thetransmittance of anode to visible light is preferably 10% or more. Thesheet resistance of anode is preferably several hundreds Ω/□ or less.The film thickness of anode depends upon the kind of material andgenerally 10 nm to 1 μm, preferably 10 to 200 nm.

Cathode

The cathode injects electrons to the electron injecting layer, theelectron transporting layer or the light emitting layer, and preferablyformed from a material having a small work function. Examples of thematerial for cathode include, but not limited to, indium, aluminum,magnesium, magnesium-indium alloy, magnesium-aluminum alloy,aluminum-lithium alloy, aluminum-scandium-lithium alloy, andmagnesium-silver alloy. Like the anode, the cathode is formed by makingthe material into a thin film by a method, such as the vapor depositionmethod and the sputtering method. The emitted light may be taken fromthe cathode, if appropriate.

Light Emitting Layer

The light emitting layer is an organic layer having a light emittingfunction and is formed from one or more layers, wherein one of thelayers comprises the first host material, the second host material, andthe light emitting material as described above.

When the light emitting layer is composed of two or more layers, thelight emitting layer or layers other than that mentioned above containsor contain a host material and a dopant material when a doping system isemployed. The major function of the host material is to promote therecombination of electrons and holes and confine excitons in the lightemitting layer. The dopant material causes the excitons generated byrecombination to emit light efficiently.

In case of a phosphorescent device, the major function of the hostmaterial is to confine the excitons generated on the dopant in the lightemitting layer.

The light emitting layer may be made into a double dopant layer, inwhich two or more kinds of dopant materials having high quantum yieldare combinedly used and each dopant material emits light with its owncolor. For example, to obtain a yellow emission, a light emitting layerformed by co-depositing a host, a red-emitting dopant and agreen-emitting dopant is used.

In a laminate of two or more light emitting layers, electrons and holesare accumulated in the interface between the light emitting layers, andtherefore, the recombination region is localized in the interfacebetween the light emitting layers, to improve the quantum efficiency.

The light emitting layer may be different in the hole injection abilityand the electron injection ability, and also in the hole transportingability and the electron transporting ability each being expressed bymobility.

The light emitting layer is formed, for example, by a known method, suchas a vapor deposition method, a spin coating method, and LB method.Alternatively, the light emitting layer may be formed by making asolution of a binder, such as resin, and the material for the lightemitting layer in a solvent into a thin film by a method such as spincoating.

The light emitting layer is preferably a molecular deposit film. Themolecular deposit film is a thin film formed by depositing a vaporizedmaterial or a film formed by solidifying a material in the state ofsolution or liquid. The molecular deposit film can be distinguished froma thin film formed by LB method (molecular build-up film) by thedifferences in the assembly structures and higher order structures andthe functional difference due to the structural differences.

The content ratio of the first host material and the second hostmaterial in the light emitting layer is not particularly limited and maybe selected accordingly, and the ratio of first host material:secondhost material is preferably 1:99 to 99:1, more preferably 10:90 to90:10, each based on mass.

The phosphorescent dopant (phosphorescent emitting material) is acompound which emits light by releasing the energy of excited tripletstate and preferably a organometallic complex comprising at least onemetal selected from Ir, Pt, Os, Au, Cu, Re, and Ru and a ligand,although not particularly limited thereto as long as emitting light byreleasing the energy of excited triplet state. A ligand having an orthometal bond is preferred. In view of obtaining a high phosphorescentquantum yield and further improving the external quantum efficiency ofelectroluminescence device, a metal complex comprising a metal selectedfrom Ir, Os, and Pt is preferred, with iridium complex, osmium complex,and platinum, particularly an ortho metallated complex thereof beingmore preferred, iridium complex and platinum complex being still morepreferred, and an ortho metallated iridium complex being particularlypreferred.

The content of the phosphorescent dopant in the light emitting layer isnot particularly limited and selected according to the use of thedevice, and preferably 0.1 to 70% by mass, and more preferably 1 to 30%by mass. If being 0.1% by mass or more, the amount of light emission issufficient. If being 70% by mass or less, the concentration quenchingcan be avoided.

Preferred examples of the organometallic complex usable as thephosphorescent dopant are shown below.

The phosphorescent dopants may be used alone or in combination of two ormore.

The emission wavelength of the phosphorescent dopant used in the lightemitting layer is not particularly limited. In a preferred embodiment,at least one of the phosphorescent dopants used in the light emittinglayer has the peak of emission wavelength of preferably 490 nm or longerand 700 nm or shorter and more preferably 490 nm or longer and 650 nm orshorter.

The phosphorescent host is a compound which confines the triplet energyof the phosphorescent dopant efficiently in the light emitting layer tocause the phosphorescent dopant to emit light efficiently. In additionto the first host material and the second host material, other compoundsmay be used as the phosphorescent host in the organic EL device of theinvention according to the use of the device.

The first host material, the second host material and a compound otherthan those may be combinedly used in the same light emitting layer asthe phosphorescent host material. If two or more light emitting layersare formed, the first host material and the second host material can beused in one light emitting layer as the phosphorescent host material anda compound other than the first host material and the second hostmaterial can be used in another light emitting layer as thephosphorescent host material. The first host material and the secondhost material may be used in an organic layer other than the lightemitting layer.

Examples of the compounds other than the first host material and thesecond host material, which are suitable as the phosphorescent host,include a carbazole derivative, a triazole derivative, a oxazolederivative, an oxadiazole derivative, an imidazole derivative, apolyarylalkane derivative, a pyrazoline derivative, a pyrazolonederivative, a phenylenediamine derivative, an arylamine derivative, anamino-substituted chalcone derivative, a styrylanthracene derivative, afluorenone derivative, a hydrazone derivative, a stilbene derivative, asilazane derivative, an aromatic tertiary amine compound, a styrylaminecompound, an aromatic methylidene compound, a porphyrin compound, ananthraquinodimethane derivative, an anthrone derivative, adiphenylquinone derivative, a thiopyran dioxide derivative, acarbodiimide derivative, a fluorenylidenemethane derivative, adistyrylpyrazine derivative, a tetracarboxylic anhydride of fused ringsuch as naphthalene and perylene, a phthalocyanine derivative, a metalcomplex of 8-quinolinol derivative, metal phthalocyanine, metalcomplexes having a ligand such as benzoxazole and benzothiazole, anelectroconductive oligomer, such as a polysilane compound, apoly(N-vinylcarbazole) derivative, an aniline copolymer, thiopheneoligomer, and a polythiophene, and a polymer such as a polythiophenederivative, a polyphenylene derivative, a polyphenylenevinylenederivative, and a polyfluorene derivative. These phosphorescent hostsother than the first host material and the second host material may beused alone or in combination of two or more. Specific examples thereofare shown below.

The thickness of the light emitting layer is preferably 5 to 50 nm, morepreferably 7 to 50 nm, and still more preferably 10 to 50 nm. If being 5nm or more, the light emitting layer is easily formed. If being 50 nm orless, the increase in driving voltage is avoided.

Electron-Donating Dopant

It is preferred for the organic EL device of the invention to contain anelectron-donating dopant in the interfacial region between the cathodeand the light emitting unit. With such a construction, the organic ELdevice has an improved luminance and an elongated lifetime. Theelectron-donating dopant is a metal having a work function of 3.8 eV orless or a compound containing such metal. Examples thereof include atleast one compound selected from alkali metal, alkali metal complex,alkali metal compound, alkaline earth metal, alkaline earth metalcomplex, alkaline earth metal compound, rare earth metal, rare earthmetal complex, and rare earth metal compound.

Examples of the alkali metal include Na (work function: 2.36 eV), K(work function: 2.28 eV), Rb (work function: 2.16 eV), and Cs (workfunction: 1.95 eV), with those having a work function of 2.9 eV or lessbeing particularly preferred. Of the above, preferred are K, Rb, and Cs,more preferred are Rb and Cs, and most preferred is Cs. Examples of thealkaline earth metal include Ca (work function: 2.9 eV), Sr (workfunction: 2.0 to 2.5 eV), and Ba (work function: 2.52 eV), with thosehaving a work function of 2.9 eV or less being particularly preferred.Examples of the rare earth metal include Sc, Y, Ce, Tb, and Yb, withthose having a work function of 2.9 eV or less being particularlypreferred.

Examples of the alkali metal compound include alkali oxide, such asLi₂O, Cs₂O, K₂O, and alkali halide, such as LiF, NaF, CsF, and KF, withLiF, Li₂O, and NaF being preferred. Examples of the alkaline earth metalcompound include BaO, SrO, CaO, and mixture thereof, such asBaxSr_(1-x)O (0<x<1) and Ba_(x)CA¹ _(-x)O (0<x<1), with BaO, SrO, andCaO being preferred. Examples of the rare earth metal compound includeYbF₃, ScF₃, ScO₃, Y₂O₃, Ce₂O₃, GdF₃, and TbF₃, with YbF₃, ScF₃, and TbF₃being preferred.

Examples of the alkali metal complex, alkaline earth metal complex, andrare earth metal are not particularly limited as long as containing atleast one metal ion selected from alkali metal ions, alkaline earthmetal ions, rare earth metal ions, respectively. The ligand ispreferably, but not limited to, quinolinol, benzoquinolinol, acridinol,phenanthridinol, hydroxyphenyloxazole, hydroxyphenylthiazole,hydroxydiaryloxadiazole, hydroxydiarylthiadiazole,hydroxyphenylpyridine, hydroxyphenylbenzimidazole, hydroxybenzotriazole,hydroxyfulborane, bipyridyl, phenanthroline, phthalocyanine, porphyrin,cyclopentadiene, β-diketones, azomethines, and derivative thereof.

The electron-donating dopant is added to the interfacial regionpreferably into a form of layer or island. The electron-donating dopantis added preferably by co-depositing the electron-donating dopant withthe organic compound (light emitting material, electron injectingmaterial, etc.) for forming the interfacial region by a resistanceheating deposition method, thereby dispersing the electron-donatingdopant into the organic material. The disperse concentration expressedby the molar ratio of the organic material and the electron-donatingdopant is 100:1 to 1:100 and preferably 5:1 to 1:5.

When the electron-donating dopant is formed into a form of layer, alight emitting material or an electron injecting material is made into alayer which serves as an organic layer in the interface, and then, theelectron-donating dopant alone is deposited by a resistance heatingdeposition method into a layer having a thickness preferably 0.1 to 15nm. When the electron-donating dopant is formed into a form of island, alight emitting material or an electron injecting material is made into aform of island which serves as an organic layer in the interface, andthen, the electron-donating dopant alone is deposited by a resistanceheating deposition method into a form of island having a thicknesspreferably 0.05 to 1 nm.

The molar ratio of the main component and the electron-donating dopantin the organic electroluminescence device of the invention is preferably5:1 to 1:5 and more preferably 2:1 to 1:2.

Electron Transporting Layer

The electron transporting layer is an organic layer disposed between thelight emitting layer and the cathode and transports electrons from thecathode to the light emitting layer. If two or more electrontransporting layers are provided, the organic layer closer to thecathode may be called an electron injecting layer in some cases. Theelectron injecting layer injects electrons from the cathode to theorganic layer unit efficiently.

An aromatic heterocyclic compound having one or more heteroatoms in itsmolecule is preferably used as the electron transporting material forthe electron transporting layer, with a nitrogen-containing ringderivative being particularly preferred. The nitrogen-containing ringderivative is preferably an aromatic ring compound having anitrogen-containing 6- or 5-membered ring or a condensed aromatic ringcompound having a nitrogen-containing 6- or 5-membered ring.

The nitrogen-containing ring derivative is preferably, for example, achelate metal complex having a nitrogen-containing ring represented byformula (AA).

R² to R⁷ of formula (AA) each independently represent a hydrogen atom, aa deuterium atom, a halogen atom, a hydroxyl group, an amino group, ahydrocarbon group having 1 to 40 carbon atoms, an alkoxy group having 1to 40 carbon atoms, an aryloxy group having 6 to 50 carbon atoms, analkoxycarbonyl group, or a heterocyclic group having 5 to 50 carbonatoms, each being optionally substituted.

The halogen atom may include fluorine, chlorine, bromine, and iodine.

The substituted amino group may include an alkylamino group, anarylamino group, and an aralkylamino group.

The alkylamino group and the aralkylamino group are represented by—NQ¹Q², wherein Q¹ and Q² each independently represent an alkyl grouphaving 1 to 20 carbon atoms or an aralkyl group having 1 to 20 carbonatoms. One of Q¹ and Q² may be a hydrogen atom or a deuterium atom.

The arylamino group is represented by —NAr¹Ar², wherein Ar¹ and Ar² eachindependently represent a non-condensed aromatic hydrocarbon group or acondensed aromatic hydrocarbon group each having 6 to 50 carbon atoms.One of Ar¹ and Ar² may be a hydrogen atom or a deuterium atom.

The hydrocarbon group having 1 to 40 carbon atoms may include an alkylgroup, an alkenyl group, a cycloalkyl group, an aryl group, and anaralkyl group.

The alkoxycarbonyl group is represented by —COOY′, wherein Y′ is analkyl group having 1 to 20 carbon atoms.

M of formula (AA) is aluminum (Al), gallium (Ga), or indium (In), withIn being preferred.

L of formula (AA) is a group represented by formula (A′) or (A″):

R⁸ to R¹² in formula (A′) each independently represent a hydrogen atom,a deuterium atom, or a substituted or unsubstituted hydrocarbon grouphaving 1 to 40 carbon atoms. The adjacent two groups may form a ringstructure. R¹³ to R²⁷ in formula (A″) each independently represent ahydrogen atom, a deuterium atom, or a substituted or unsubstitutedhydrocarbon group having 1 to 40 carbon atoms. The adjacent two groupsmay form a ring structure.

Examples of the hydrocarbon group having 1 to 40 carbon atoms for R⁸ toR¹² and R¹³ to R²⁷ in formulae (A′) and (A″) are the same as thosedescribed above with respect to R² to R⁷ of formula (A). Examples of thedivalent group formed by the adjacent two groups of R⁸ to R¹² and R¹³ toR²⁷ which completes the ring structure include tetramethylene group,pentamethylene group, hexamethylene group, diphenylmethane-2,2′-diylgroup, diphenylethane-3,3′-diyl group, and diphenylpropane-4,4′-diylgroup.

The electron transporting compound for the electron transporting layeris preferably a metal complex including 8-hydroxyquinoline or itsderivative, an oxadiazole derivative, and a nitrogen-containingheterocyclic derivative. Examples of the metal complex including8-hydroxyquinoline or its derivative include a metal chelate oxinoidincluding a chelated oxine (generally, 8-quinolinol or8-hydroxyquinoline), for example, tris(8-quinolinol)aluminum. Examplesof the oxadiazole derivative are shown below.

In the above formulae, each of Ar¹⁷, Ar¹⁸, Ar¹⁹, Ar²¹, Ar²², and Ar²⁵ isa substituted or unsubstituted aromatic hydrocarbon group or asubstituted or unsubstituted condensed aromatic hydrocarbon group eachhaving 6 to 50 carbon atoms, and Ar¹⁷ and Ar¹⁸, Ar¹⁹ and Ar²¹, and Ar²²and Ar²⁵ may be the same or different. Examples of the aromatichydrocarbon group and the condensed aromatic hydrocarbon group includephenyl group, naphthyl group, biphenyl group, anthranyl group, perylenylgroup, and pyrenyl group. The optional substituent may be an alkyl grouphaving 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbonatoms or a cyano group.

Each of Ar²⁰, Ar²³, and Ar²⁴ is a substituted or unsubstituted bivalentaromatic hydrocarbon group or a substituted or unsubstituted bivalentcondensed aromatic hydrocarbon group each having 6 to 50 carbon atoms,and Ar²³ and Ar²⁴ may be the same or different. Examples of the bivalentaromatic hydrocarbon group or the bivalent condensed aromatichydrocarbon group include phenylene group, naphthylene group,biphenylene group, anthranylene group, perylenylene group, andpyrenylene group. The optional substituent may be an alkyl group having1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms or acyano group.

Electron transporting compounds which have a good thin film-formingproperty are preferably used. Examples of the electron transportingcompound are shown below.

Examples of the nitrogen-containing heterocyclic derivative for use asthe electron transporting compound include a nitrogen-containingheterocyclic derivative having the following formulae but exclusive ofmetal complex, for example, a compound having a 5- or 6-membered ringwhich has the skeleton represented by formula (B) or having thestructure represented by formula (C).

In formula (C), X is a carbon atom or a nitrogen atom. Z₁ and Z₂ eachindependently represent a group of atoms for completing thenitrogen-containing heteroring.

The nitrogen-containing heterocyclic derivative is more preferably anorganic compound which has a nitrogen-containing aromatic polycyclicring comprising a 5-membered ring or a 6-membered ring. If two or morenitrogen atoms are included, the nitrogen-containing aromatic polycycliccompound preferably has a skeleton of a combination of (B) and (C) or acombination of (B) and (D).

The nitrogen-containing group of the nitrogen-containing aromaticpolycyclic compound is selected, for example, from thenitrogen-containing heterocyclic groups shown below.

In the above formulae, R is an aromatic hydrocarbon group or a condensedaromatic hydrocarbon group each having 6 to 40 carbon atoms, an aromaticheterocyclic group or a condensed aromatic heterocyclic group eachhaving 3 to 40 carbon atoms, an alkyl group having 1 to 20 carbon atoms,or an alkoxy group having 1 to 20 carbon atoms; and n is an integer of 0to 5. If n is an integer of 2 or more, R groups may be the same ordifferent.

More preferred is a nitrogen-containing heterocyclic derivativerepresented by the following formula:HAr-L¹-Ar¹-Ar²  (D1)wherein HAr is a substitute or unsubstituted nitrogen-containingheterocyclic group having 3 to 40 carbon atoms; L¹ is a single bond, asubstituted or unsubstituted aromatic hydrocarbon group or condensedaromatic hydrocarbon group each having 6 to 40 carbon atoms, or asubstituted or unsubstituted aromatic heterocyclic group or condensedaromatic heterocyclic group each having 3 to 40 carbon atoms; Ar¹ is asubstitute or unsubstituted divalent aromatic hydrocarbon group having 6to 40 carbon atoms; and Ar² is a substitute or unsubstituted aromatichydrocarbon group or condensed aromatic hydrocarbon group each having 6to 40 carbon atoms or a substituted or unsubstituted aromaticheterocyclic group or condensed aromatic heterocyclic group each having3 to 40 carbon atoms.

HAr of formula (D1) is selected, for example, from the following groups:

L¹ of formula (D1) is selected, for example, from the following groups:

Ar¹ of formula (D1) is selected, for example, from the followingarylanthranyl groups represented by formula (D2) or (D3):

In the above formulae (D2) and (D3), R¹ to R¹⁴ are each independently ahydrogen atom, a deuterium atom, a halogen atom, an alkyl group having 1to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, anaryloxy group having 6 to 40 carbon atoms, a substituted orunsubstituted aromatic hydrocarbon group or condensed aromatichydrocarbon group each having 6 to 40 carbon atoms, or a substituted orunsubstituted aromatic heterocyclic group or condensed aromaticheterocyclic group each having 3 to 40 carbon atoms; and Ar³ is asubstituted or unsubstituted aromatic hydrocarbon group or condensedaromatic hydrocarbon group each having 6 to 40 carbon atoms or asubstituted or unsubstituted aromatic heterocyclic group or condensedaromatic heterocyclic group each having 3 to 40 carbon atoms. R¹- to R⁸may be all selected from a hydrogen atom and a deuterium atom.

Ar² of formula (D1) is selected, for example, from the following groups:

In addition, the following compound is preferably used as thenitrogen-containing aromatic polycyclic compound for use as the electrontransporting compound.

In the formula (D4), R₁ to R₄ each independently represent a hydrogenatom, a deuterium atom, a substituted or unsubstituted aliphatic grouphaving 1 to 20 carbon atoms, a substituted or unsubstituted alicyclicgroup having 3 to 20 carbon atoms, a substituted or unsubstitutedaromatic group having 6 to 50 carbon atoms, or a substituted orunsubstituted heterocyclic group having 3 to 50 carbon atoms; and X₁ andX₂ each independently represent an oxygen atom, a sulfur atom, ordicyanomethylene group.

Further, the following compound is also suitable as the electrontransporting compound.

In the formula (D5), R¹, R², R³, and R⁴ may be the same or different andeach represents an aromatic hydrocarbon group or a condensed aromatichydrocarbon group each represented by the following formula (D6):

In the formula (D6), R⁵, R⁶, R⁷, R⁸, and R⁹ may be the same or differentand each represents a hydrogen atom, a deuterium atom, a saturated orunsaturated alkoxyl group having 1 to 20 carbon atoms, a saturated orunsaturated alkyl group having 1 to 20 carbon atoms, an amino group, oran alkylamino group having 1 to 20 carbon atoms. At least one of R⁵, R⁶,R⁷, R⁸, and R⁹ is a group other than hydrogen atom and deuterium atom.

Further, a polymer having the nitrogen-containing heterocyclic group orthe nitrogen-containing heterocyclic derivative is also usable as theelectron transporting compound.

It is particularly preferred for the electron transporting layer of theorganic EL of the invention to contain at least one of thenitrogen-containing heterocyclic derivatives represented by thefollowing formulae (E) to (G).

In the formulae (E) to (G), Z¹, Z², and Z³ each independently representa nitrogen atom or a carbon atom.

R¹ and R² each independently represent a substituted or unsubstitutedaryl group having 6 to 50 ring carbon atoms, a substituted orunsubstituted heteroaryl group having 5 to 50 ring atoms, a substitutedor unsubstituted alkyl group having 1 to 20 carbon atoms, a substitutedor unsubstituted haloalkyl group having 1 to 20 carbon atoms, or asubstituted or unsubstituted alkoxyl group having 1 to 20 carbon atoms.

The subscript n is an integer of 0 to 5. If n is an integer of 2 ormore, R¹ groups may be the same or different from each other. Theadjacent two R¹ groups may bond to each other to form a substituted orunsubstituted hydrocarbon ring.

Ar¹ represents a substituted or unsubstituted aryl group having 6 to 50ring carbon atoms or a substituted or unsubstituted heteroaryl grouphaving 5 to 50 ring atoms.

Ar² represents a hydrogen atom, a substituted or unsubstituted alkylgroup having 1 to 20 carbon atoms, a substituted or unsubstitutedhaloalkyl group having 1 to 20 carbon atoms, a substituted orunsubstituted alkoxyl group having 1 to 20 carbon atoms, a substitutedor unsubstituted aryl group having 6 to 50 ring carbon atoms, or asubstituted or unsubstituted heteroaryl group having 5 to 50 ring atoms.

However, one of Ar¹ and Ar² is a substituted or unsubstituted condensedaromatic hydrocarbon group having 10 to 50 ring carbon atoms or asubstituted or unsubstituted condensed aromatic heterocyclic grouphaving 9 to 50 ring atoms.

Ar³ represents a substituted or unsubstituted arylene group having 6 to50 ring carbon atoms or a substituted or unsubstituted heteroarylenegroup having 5 to 50 ring atoms.

L¹, L², and L³ each independently represent a single bond, a substitutedor unsubstituted arylene group having 6 to 50 ring carbon atoms or asubstituted or unsubstituted divalent condensed aromatic heterocyclicgroup having 9 to 50 ring atoms.

Examples of the aryl group having 6 to 50 ring carbon atoms includephenyl group, naphthyl group, anthryl group, phenanthryl group,naphthacenyl group, chrysenyl group, pyrenyl group, biphenyl group,terphenyl group, tolyl group, fluoranthenyl group, and fluorenyl group.

Examples of the heteroaryl group having 5 to 50 ring atoms includepyrrolyl group, furyl group, thienyl group, silolyl group, pyridylgroup, quinolyl group, isoquinolyl group, benzofuryl group, imidazolylgroup, pyrimidyl group, carbazolyl group, selenophenyl group,oxadiazolyl group, triazolyl group, pyrazinyl group, pyridazinyl group,triazinyl group, quinoxalinyl group, acridinyl group,imidazo[1,2-a]pyridinyl group, and imidazo[1,2-a]pyrimidinyl.

Examples of the alkyl group having 1 to 20 carbon atoms include methylgroup, ethyl group, propyl group, butyl group, pentyl group, and hexylgroup.

Examples of the haloalkyl group having 1 to 20 carbon atoms include thegroups obtained by replacing one or more hydrogen atoms of the alkylgroup mentioned above with at least one halogen atom selected fromfluorine, chlorine, iodine, and bromine.

Examples of the alkyl moiety of the alkoxyl group having 1 to 20 carbonatoms include the alkyl group mentioned above.

Examples of the arylene groups include the groups obtained by removingone hydrogen atom from the aryl group mentioned above.

Examples of the divalent condensed aromatic heterocyclic group having 9to 50 ring atoms include the groups obtained by removing one hydrogenatom from the condensed aromatic heterocyclic group mentioned above asthe heteroaryl group.

The thickness of the electron transporting layer is preferably 1 to 100nm, although not particularly limited thereto.

The electron injecting layer which may be formed adjacent to theelectron transporting layer preferably includes an inorganic compound,such as an insulating material and a semiconductor in addition to thenitrogen-containing ring derivative. The insulating material orsemiconductor incorporated into the electron injecting layer effectivelyprevents the leak of electric current to enhance the electron injectingproperties.

The insulating material is preferably at least one metal compoundselected from the group consisting of alkali metal chalcogenides,alkaline earth metal chalcogenides, alkali metal halides and alkalineearth metal halides. The alkali metal chalcogenide, etc. incorporatedinto the electron injecting layer further enhances the electroninjecting properties. Preferred examples of the alkali metalchalcogenides include Li₂O, K₂O, Na₂S, Na₂Se and Na₂O, and preferredexamples of the alkaline earth metal chalcogenides include CaO, BaO,SrO, BeO, BaS and CaSe. Preferred examples of the alkali metal halidesinclude LiF, NaF, KF, LiCl, KCl and NaCl. Examples of the alkaline earthmetal halides include fluorides such as CaF₂, BaF₂, SrF₂, MgF₂ and BeF₂and halides other than fluorides.

Examples of the semiconductor may include oxide, nitride or oxynitrideeach containing at least one element selected from the group consistingof Ba, Ca, Sr, Yb, Al, Ga, In, Li, Na, Cd, Mg, Si, Ta, Sb and Zn. Thesemiconductor may be used singly or in combination of two or more. Theinorganic compound forming the electron injecting layer preferably formsa microcrystalline or amorphous insulating thin film. When the electroninjecting layer is formed from such an insulating thin film, the thinfilm is made more uniform to decrease the pixel defects such as darkspots. Examples of such inorganic compound include alkali metalchalcogenides, alkaline earth metal chalcogenides, alkali metal halidesand alkaline earth metal halide, each being described above.

The thickness of the layer including the insulating material or thesemiconductor is preferably about 0.1 to 15 nm. The electron injectinglayer may be included with the electron-donating dopant described above.

Hole Transporting Layer

The hole transporting layer is an organic layer formed between the lightemitting layer and the anode and has a function of transporting holesfrom the anode to the light emitting layer. When the hole transportinglayer is formed by two or more layers, the layer closer to the anode maybe defined as the hole injecting layer in some cases. The hole injectinglayer has a function of efficiently injecting holes from the anode tothe organic layer unit.

An aromatic amine compound, for example, the aromatic amine derivativerepresented by formula (H), is also preferably used as the material forforming the hole transporting layer.

In the formula (H), each of Ar¹ to Ar⁴ represents a substituted orunsubstituted aromatic hydrocarbon group or condensed aromatichydrocarbon group having 6 to 50 ring carbon atoms, a substituted orunsubstituted aromatic heterocyclic group or condensed aromaticheterocyclic group having 5 to 50 ring atoms, or a group wherein thearomatic hydrocarbon group or condensed aromatic hydrocarbon group andthe aromatic heterocyclic group or condensed aromatic heterocyclic groupare boned to each other.

L represents a substituted or unsubstituted aromatic hydrocarbon groupor condensed aromatic hydrocarbon group each having 6 to 50 ring carbonatoms or a substituted or unsubstituted aromatic heterocyclic group orcondensed aromatic heterocyclic group each having 5 to 50 ring atoms.

Specific examples of the compound represented by the formula (H) areshown below.

The aromatic amine represented by the formula (J) is also preferablyused as the material for forming the hole transporting layer.

In the formula (J), each of Ar¹ to Ar³ is defined in the same manner asin the definition of Ar¹ to Ar⁴ of the formula (H). The specificexamples of the compounds represented by the formula (J) are shownbelow, although not limited thereto.

The hole transporting layer of the organic EL device of the inventionmay be made into two-layered structure of a first hole transportinglayer (anode side) and a second hole transporting layer (cathode side).

The thickness of the hole transporting layer is preferably 10 to 200 nm,although not particularly limited thereto.

The organic EL device of the invention may have a layer comprising anacceptor material which is attached to the anode side of each of thehole transporting layer and the first hole transporting layer. With sucha layer, it is expected that the driving voltage is lowered and theproduction cost is reduced.

The acceptor material is preferably a compound represented by theformula (K):

wherein R₂₁ to R₂₆ may be the same or different and each independentlyrepresent a cyano group, —CONH₂, a carboxyl group, or —COOR₂₇ whereinR₂₇ represents an alkyl group having 1 to 20 carbon atoms or acycloalkyl group having 3 to 20 carbon atoms. One or more of a pair ofR₂₁ and R₂₂, a pair of R₂₃ and R₂₄, and a pair of R₂₅ and R₂₆ may bondto each other to form a group represented by —CO—O—CO—.

Examples of R₂₇ include methyl group, ethyl group, n-propyl group,isopropyl group, n-butyl group, isobutyl group, t-butyl group,cyclopentyl group, and cyclohexyl group.

The thickness of the layer comprising the acceptor material ispreferably 5 to 20 nm, although not particularly limited thereto.

N/P Doping

The carrier injecting properties of the hole transporting layer and theelectron transporting layer can be controlled by, as described in JP3695714B, the doping (n) with a donor material or the doping (p) with anacceptor material.

A typical example of the n-doping is an electron transporting materialdoped with a metal, such as Li and Cs, and a typical example of thep-doping is a hole transporting material doped with an acceptor materialsuch as, F₄TCNQ (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane).

Space Layer

For example, in an organic EL device wherein a fluorescent lightemitting layer and a phosphorescent light emitting layer are laminated,a space layer is disposed between the fluorescent light emitting layerand the phosphorescent light emitting layer to prevent the diffusion ofexcitons generated in the phosphorescent light emitting layer to thefluorescent light emitting layer or to control the carrier balance. Thespace layer may be disposed between two or more phosphorescent lightemitting layers.

Since the space layer is disposed between the light emitting layers, amaterial combining the electron transporting ability and the holetransporting ability is preferably used for forming the space layer. Toprevent the diffusion of triplet energy in the adjacent phosphorescentlight emitting layer, the triplet energy of the material for the spacelayer is preferably 2.6 eV or more. The materials described with respectto the hole transporting layer are usable as the material for the spacelayer.

Blocking Layer

The organic EL device of the invention preferably has a blocking layer,such as an electron blocking layer, a hole blocking layer, and a tripletblocking layer, which is disposed adjacent to the light emitting layer.The electron blocking layer is a layer which prevents the diffusion ofelectrons from the light emitting layer to the hole transporting layer.The hole blocking layer is a layer which prevents the diffusion of holesfrom the light emitting layer to the electron transporting layer. Thematerial for organic EL device of the invention is also usable as thematerial for the hole blocking layer.

The triplet blocking layer prevents the diffusion of triplet excitonsgenerated in the light emitting layer to adjacent layers and has afunction of confining the triplet excitons in the light emitting layer,thereby preventing the deactivation of energy on molecules other thanthe emitting dopant of triplet excitons, for example, on molecules inthe electron transporting layer.

If a phosphorescent device having a triplet blocking layer satisfies thefollowing energy relationship:E^(T) _(d)<E^(T) _(TB)wherein E^(T) _(d) is the triplet energy of the phosphorescent dopant inthe light emitting layer and E^(T) _(TB) is the triplet energy of thecompound forming the triplet blocking layer,the triplet excitons of phosphorescent dopant are confined (not diffuseto other molecules). Therefore, the energy deactivation process otherthan the emission on the phosphorescent dopant may be prevented to causethe emission with high efficiency. However, even in case of satisfyingthe relationship of E^(T) _(d)<E^(T) _(TB), the triplet excitons maymove into other molecules if the energy difference (ΔE^(T)=E^(T)_(TB)−E^(T) _(d)) is small, because the energy difference ΔE^(T) may beovercome by the absorption of ambient heat energy when driving a deviceat around room temperature as generally employed in practical drive ofdevice. As compared with the fluorescent emission, the phosphorescentemission is relatively likely to be affected by the diffusion ofexcitons due to the heat absorption because the lifetime of tripletexcitons is longer. Therefore, as for the energy difference ΔE^(T), thelarger as compared with the heat energy of room temperature, the better.The energy difference LET is more preferably 0.1 eV or more andparticularly preferably 0.2 eV or more.

The electron mobility of the material for the triplet blocking layer ispreferably 10⁻⁶ cm²/Vs or more at an electric field strength in a rangeof 0.04 to 0.5 MV/cm. There are several methods for measuring theelectron mobility of organic material, for example, Time of Flightmethod. In the present invention, the electron mobility is determined byimpedance spectroscopy.

The electron mobility of the electron injecting layer is preferably 10⁻⁶cm²/Vs or more at an electric field strength in a range of 0.04 to 0.5MV/cm. Within the above range, the injection of electrons from thecathode to the electron transporting layer is promoted and the injectionof electrons to the adjacent blocking layer and light emitting layer isalso promoted, thereby enabling to drive a device at lower voltage.

EXAMPLES

The present invention will be described in more detail with reference tothe examples. However, it should be noted that the scope of theinvention is not limited to the following examples.

Synthesis of Material for Organic EL Device Synthesis Example 1Synthesis of Compound H1 Synthesis Example (1-1) Synthesis ofIntermediate 1

In argon stream, a mixture obtained by successively mixing2-nitro-1,4-dibromobenzene (11.2 g, 40 mmol), phenylboronic acid (4.9 g,40 mmol), tetrakis(triphenylphosphine)palladium (1.39 g, 1.2 mmol),toluene (120 mL), and a 2M aqueous solution of sodium carbonate (60 mL)was refluxed under heating for 8 h.

After cooling the reaction liquid to room temperature, the organic layerwas separated and the organic solvent was removed from the organic layerby distillation under reduced pressure. The obtained residue waspurified by a silica gel column chromatography to obtain theintermediate 1 (6.6 g, yield: 59%). The identification of theintermediate 1 was made by FD-MS (field desorption mass spectrometry)analysis.

Synthesis Example (1-2) Synthesis of Intermediate 2

In argon stream, a mixture obtained by successively mixing theintermediate 1 (6.6 g, 23.7 mmol), triphenylphosphine (15.6 g, 59.3mmol), and o-dichlorobenzene (24 mL) was heated at 180° C. for 8 h.

After cooling the reaction liquid to room temperature, the reactionproduct was purified by a silica gel column chromatography to obtain theintermediate 2 (4 g, yield: 68%). The identification of the intermediate2 was made by FD-MS (field desorption mass spectrometry) analysis.

Synthesis Example (1-3) Synthesis of Intermediate 3

The procedure of Synthesis of Intermediate 1 was repeated except forusing the intermediate 2 in place of 2-nitro-1,4-dibromobenzene andusing 9-phenylcarbazole-3-ylboronic acid in place of phenylboronic acid.The obtained compound was identified as the intermediate 3 by FD-MS(field desorption mass spectrometry) analysis.

Synthesis Example (1-4) Synthesis of Compound H1

In argon stream, a mixture obtained by successively mixing theintermediate 3 (1.6 g, 3.9 mmol), 4-bromobenzonitrile (0.71 g, 3.9mmol), tris(dibenzylideneacetone)dipalladium (0.071 g, 0.078 mmol),tri-t-butylphosphonium tetrafluoroborate (0.091 g, 0.31 mmol), sodiumt-butoxide (0.53 g, 5.5 mmol), and dry toluene (20 mL) was refluxedunder heating for 8 h.

After cooling the reaction liquid to room temperature, the organic layerwas separated and the organic solvent was removed from the organic layerby distillation under reduced pressure. The obtained residue waspurified by a silica gel column chromatography to obtain 0.79 g of whitesolid (H1).

The obtained compound was measured for FD-MS (field desorption massspectrometry), maximum ultraviolet absorption wavelength (UV(PhMe) λmax)in toluene, and maximum fluorescence wavelength (FL(PhMe, λex=300 nm)λmax) in toluene. The results are shown below.

-   FDMS: calcd. for C₃₇H₂₃N₃=509, found m/z=509 (M+)-   (UV(PhMe) λmax: 324 nm-   FL(PhMe, λex=300 nm) λmax: 376 nm

Synthesis Example 2 Synthesis of Compound H2

The procedure of Synthesis of Compound H1 was repeated except for using4′-bromobiphenyl-3-carbonitrile in place of 4-bromobenzonitrile.

The obtained compound was measured for FD-MS (field desorption massspectrometry), maximum ultraviolet absorption wavelength ((UV(PhMe)λmax) in toluene, and maximum fluorescence wavelength (FL(PhMe, λex=300nm) λmax) in toluene. The results are shown below.

-   FDMS: calcd. for C₄₃H₂₇N₃=585, found m/z=585 (M+)-   (UV(PhMe) λmax: 322 nm-   FL(PhMe, λex=300 nm) λmax: 375 nm

Synthesis Example 3 Synthesis of Compound H3

The procedure of Synthesis of Compound H1 was repeated except for using4′-bromobiphenyl-4-carbonitrile in place of 4-bromobenzonitrile.

The obtained compound was measured for FD-MS (field desorption massspectrometry), maximum ultraviolet absorption wavelength ((UV(PhMe)λmax) in toluene, and maximum fluorescence wavelength (FL(PhMe, λex=300nm) λmax) in toluene. The results are shown below.

-   FDMS: calcd. for C₄₃H₂₇N₃=585, found m/z=585 (M+)-   (UV(PhMe) λmax: 324 nm-   FL(PhMe, λex=300 nm) λmax: 393 nm

Synthesis Example 4 Synthesis of Compound H4

The procedure of Synthesis of Compound H1 was repeated except for using3′-bromobiphenyl-4-carbonitrile in place of 4-bromobenzonitrile.

The obtained compound was measured for FD-MS (field desorption massspectrometry), maximum ultraviolet absorption wavelength ((UV(PhMe)λmax) in toluene, and maximum fluorescence wavelength (FL(PhMe, λex=300nm) λmax) in toluene. The results are shown below.

-   FDMS: calcd. for C₄₃H₂₇N₃=585, found m/z=585 (M+)-   (UV(PhMe) λmax: 322 nm-   FL(PhMe, λex=300 nm) λmax: 376 nm

Synthesis Example 5 Synthesis of Compound H5 Synthesis Example (5-1)Synthesis of Intermediate 4

The procedure of Synthesis of Intermediate 1 was repeated except forusing 3-bromocarbazole in place of 2-nitro-1,4-dibromobenzene and using9-phenylcarbazole-3-ylboronic acid in place of phenylboronic acid.

The obtained compound was identified as the intermediate 4 by FD-MS(field desorption mass spectrometry) analysis.

Synthesis Example (5-2) Synthesis of Compound H5

The procedure of Synthesis of Compound H1 was repeated except for usingthe intermediate 4 in place of the intermediate 3.

The obtained compound was measured for FD-MS (field desorption massspectrometry), maximum ultraviolet absorption wavelength ((UV(PhMe)λmax) in toluene, and maximum fluorescence wavelength (FL(PhMe, λex=300nm) λmax) in toluene. The results are shown below.

-   FDMS: calcd. for C₃₇H₂₃N₃=509, found m/z=509 (M+)-   (UV(PhMe) λmax: 339 nm-   FL(PhMe, λex=300 nm) λmax: 404 nm

Synthesis Example 6 Synthesis of Compound H6

The procedure of Synthesis of Compound H1 was repeated except for using4′-bromobiphenyl-3-carbonitrile in place of 4-bromobenzonitrile andusing the intermediate 4 in place of the intermediate 3.

The obtained compound was measured for FD-MS (field desorption massspectrometry). The result is shown below.

-   FDMS: calcd. for C₄₃H₂₇N₃=585, found m/z=585 (M+)

Synthesis Example 7 Synthesis of Compound H7

The procedure of Synthesis of Compound H1 was repeated except for using4′-bromobiphenyl-4-carbonitrile in place of 4-bromobenzonitrile andusing the intermediate 4 in place of the intermediate 3.

The obtained compound was measured for FD-MS (field desorption massspectrometry). The result is shown below.

-   FDMS: calcd. for C₄₃H₂₇N₃=585, found m/z=585 (M+)

Synthesis Example 8 Synthesis of Compound H8

The procedure of Synthesis of Compound H1 was repeated except for using3′-bromobiphenyl-4-carbonitrile in place of 4-bromobenzonitrile andusing the intermediate 4 in place of the intermediate 3.

The obtained compound was measured for FD-MS (field desorption massspectrometry). The result is shown below.

-   FDMS: calcd. for C₄₃H₂₇N₃=585, found m/z=585 (M+)

Synthesis Example 9 Synthesis of Compound H9

The procedure of Synthesis of Compound H1 was repeated except for using3′-bromobiphenyl-3-carbonitrile in place of 4-bromobenzonitrile andusing the intermediate 4 in place of the intermediate 3.

The obtained compound was measured for FD-MS (field desorption massspectrometry). The result is shown below.

-   FDMS: calcd. for C₄₃H₂₇N₃=585, found m/z=585 (M+)

Synthesis Example 10 Synthesis of Compound H10 Synthesis Example (10-1)Synthesis of Intermediate 5

The procedure of Synthesis of Intermediate 1 was repeated except forusing 1-bromo-4-iodobenzene in place of 2-nitro-1,4-dibromobenzene andusing 9-phenylcarbazole-3-ylboronic acid in place of phenylboronic acid.

The obtained compound was identified as the intermediate 5 by FD-MS(field desorption mass spectrometry) analysis.

Synthesis Example (10-2) Synthesis of Intermediate 6

In argon stream, a mixture obtained by successively mixing theintermediate 5 (10 g, 25 mmol), bis(pinacolato)diboron (8.3 g, 33 mmol),dichloromethane adduct of[1,1′-bis(diphenylphosphino)ferrocene]palladium(II) dichloride (0.62 g,0.75 mmol), potassium acetate (7.4 g, 75 mmol), andN,N-dimethylformamide (170 mL) was refluxed under heating for 8 h.

After cooling the reaction liquid to room temperature, the organic layerwas separated and the organic solvent was removed from the organic layerby distillation under reduced pressure. The obtained residue waspurified by a silica gel column chromatography to obtain theintermediate 6 (10 g, yield: 91%).

The identification of the intermediate 6 was made by FD-MS (fielddesorption mass spectrometry) analysis.

Synthesis Example (10-3) Synthesis of Intermediate 7

The procedure of Synthesis of Intermediate 1 was repeated except forusing 3-bromocarbazole in place of 2-nitro-1,4-dibromobenzene and usingthe intermediate 6 in place of phenylboronic acid. The obtained compoundwas identified as the intermediate 7 by FD-MS (field desorption massspectrometry) analysis.

Synthesis Example (10-4) Synthesis of H10

The procedure of Synthesis of Compound H1 was repeated except for using4′-bromobiphenyl-4-carbonitrile in place of 4-bromobenzonitrile andusing the intermediate 7 in place of the intermediate 3.

The obtained compound was measured for FD-MS (field desorption massspectrometry). The result is shown below.

-   FDMS: calcd. for C₄₉H₃₁N₃=661, found m/z=661 (M+)

Synthesis Example 11 Synthesis of Compound H11

The procedure of Synthesis of Compound H1 was repeated except for using3′-bromobiphenyl-4-carbonitrile in place of 4-bromobenzonitrile andusing the intermediate 7 in place of the intermediate 3.

The obtained compound was measured for FD-MS (field desorption massspectrometry). The result is shown below.

-   FDMS: calcd. for C₄₉H₃₁N₃=661, found m/z=661 (M+)

Synthesis Example 12 Synthesis of Compound H12

The procedure of Synthesis of Compound H1 was repeated except for using2-bromo-8-cyanodibenzofuran in place of 4-bromobenzonitrile and usingthe intermediate 4 in place of the intermediate 3.

The obtained compound was measured for FD-MS (field desorption massspectrometry). The result is shown below.

FDMS: calcd. for C₄₃H₂₅N₃O=599, found m/z=599 (M+)

Synthesis Example 13 Synthesis of Compound H13 Synthesis Example (13-1)Synthesis of Intermediate 8

The procedure of Synthesis of Intermediate 1 was repeated except forusing 4-bromobenzonitrile in place of 2-nitro-1,4-dibromobenzene andusing 9-phenylcarbazole-3-ylboronic acid in place of phenylboronic acid.

The obtained compound was identified as the intermediate 8 by FD-MS(field desorption mass spectrometry) analysis.

Synthesis Example (13-2) Synthesis of Intermediate 9

In argon stream, a mixture obtained by successively mixingN,N-dimethylformamide (80 mL), the intermediate 8 (5.6 g, 16.3 mmol),and N-bromosuccinimide (3.5 g, 19.5 mmol) was stirred at 0° C. for 8 h.

After returning the temperature to room temperature, the reaction liquidwas added with distilled water and then filtered. The obtained solid waspurified by silica gel column chromatography to obtain the intermediate9 (6.2 g, yield: 90%). The identification of the intermediate 9 was madeby FD-MS (field desorption mass spectrometry) analysis.

Synthesis Example (13-3) Synthesis of Compound H13

The procedure of Synthesis of Intermediate 1 was repeated except forusing the intermediate 9 in place of 2-nitro-1,4-dibromobenzene andusing 9-phenylcarbazole-3-ylboronic acid in place of phenylboronic acid.

The obtained compound was measured for FD-MS (field desorption massspectrometry). The result is shown below.

FDMS: calcd. for C₄₃H₂₇N₃=585, found m/z=585 (M+)

Synthesis Example 14 Synthesis of Compound H14

The procedure of Synthesis of Intermediate 1 was repeated except forusing 3,5-dibromobenzonitrile (1 equiv) in place of2-nitro-1,4-dibromobenzene and using 9-phenylcarbazole-3-ylboronic acid(2 equiv) in place of phenylboronic acid.

The obtained compound was measured for FD-MS (field desorption massspectrometry). The result is shown below.

-   FDMS, calcd for C₄₃H₂₇N₃=585, found m/z=585 (M+)

Synthesis Example 15 Synthesis of Compound H15

The procedure of Synthesis of Compound H1 was repeated except for using2-bromo-8-cyanodibenzofuran in place of 4-bromobenzonitrile. Theobtained compound was measured for FD-MS (field desorption massspectrometry). The result is shown below.

-   FDMS: calcd. for C₄₃H₂₅N₃O=599, found m/z=599 (M+)

Synthesis Example 16 Synthesis of Compound H16

The procedure of Synthesis of Compound H1 was repeated except for using2-bromo-8-cyanodibenzothiophene in place of 4-bromobenzonitrile. Theobtained compound was measured for FD-MS (field desorption massspectrometry). The result is shown below.

-   FDMS: calcd. for C₄₃H₂₅N₃S=615, found m/z=615 (M+)

Synthesis Example 17 Synthesis of Compound H17

The procedure of Synthesis of Compound H1 was repeated except for using2-bromo-8-cyanodibenzothiophene in place of 4-bromobenzonitrile andusing the intermediate 4 in place of the intermediate 3. The obtainedcompound was measured for FD-MS (field desorption mass spectrometry).The result is shown below.

-   FDMS: calcd. for C₄₃H₂₅N₃S=615, found m/z=615 (M+)    Production of Organic EL Device and Evaluation of Emission    Performance

Example 1

Production of Organic EL Device

A glass substrate of 25 mm×75 mm×1.1 mm thickness having an ITOtransparent electrode (product of Geomatec Company) was cleaned byultrasonic cleaning in isopropyl alcohol for 5 min and then UV ozonecleaning for 30 min.

The cleaned glass substrate was mounted to a substrate holder of avacuum vapor deposition apparatus. The electron accepting compound C-1(acceptor) shown below was vapor-deposited so as to cover thetransparent electrode to form a compound C-1 film with a thickness of 5nm. On the compound C-1 film, a first hole transporting material(aromatic amine derivative (compound X1) shown below) wasvapor-deposited to form a first hole transporting layer with a thicknessof 65 nm. Successively after forming the first hole transporting layer,a second hole transporting material (aromatic amine derivative (compoundX2) shown below) was vapor-deposited to form a second hole transportinglayer with a thickness of 10 nm.

On the second hole transporting layer, the host material 1, the hostmaterial 2, each being listed in Table 1 and Ir(bzq)₃ (phosphorescentemitting material) shown below were co-deposited to form aphosphorescent light emitting layer with a thickness of 25 nm. Theconcentration in the light emitting layer was 10.0% by mass forIr(bzq)₃, 45.0% by mass for the host compound 1, and 45.0% by mass forthe host compound 2. The co-deposited film works as a light emittinglayer.

Successively after forming the light emitting layer, the compound ETshown below was vapor-deposited into a film with a thickness of 35 nm.The compound ET film works as an electron transporting layer.

Then, LiF was vapor-deposited into a film with a thickness of 1 nm at afilm-forming speed of 0.1 Å/min to form an electron injecting electrode(cathode). On the LiF film, metallic Al was vapor-deposited to form ametallic cathode with a thickness of 80 nm, thereby obtaining an organicEL device.

The compounds used in the examples and comparative examples are shownbelow.

Evaluation of Emission Performance of Organic EL Device

Each of the obtained organic EL devices was measured for the emissionefficiency at room temperature by driving the device at constant DCcurrent (current density: 1 mA/cm²) and measured for 80% lifetime at aninitial luminance of 10,000 cd/m² (time taken until the luminance wasreduced to 80% of the initial luminance when driving the device atconstant current). The results are shown in Table 1.

Examples 2 to 5 and Comparative Example 1

In the same manner as in Example 1 except for forming the light emittinglayer by using each host material 1 and host material 2 shown in Table2, each organic EL device was produced.

The emission efficiency and 80% lifetime of each organic EL device areshown in Table 1.

TABLE 1 Emission 80% Light emitting layer efficiency Lifetime Hostmaterial 1 Host material 2 (cd/A) (h) Example 1 compound H1 compound F268 1040 Example 2 compound H1 compound F3 68 800 Example 3 compound H3compound F2 66 800 Example 4 compound H4 compound F2 70 1120 Example 5compound H5 compound F2 60 1040 Comparative compound F1 compound F3 50480 Example 1

As seen from Table 1, the organic EL devices of Examples 1 to 5, whereinthe combination of the first host material represented by formula (A)(compounds H1 and H3 to H5) and the second host material represented byformula (1) (compounds F2 and F3) was used as the host material(co-host) of the light emitting layer, showed good emission efficiency.In addition, the organic EL devices of Examples 1 to 5 showed longerlifetime as compared with the organic EL device of Comparative Example 1which employed the co-host of the compound F1 and the compound F3 eachhaving a similar central skeleton but having no cyano substituent at itsterminal end.

Example 6

Production of Organic EL Device

A glass substrate of 25 mm×75 mm×1.1 mm thickness having an ITOtransparent electrode (anode, 70 nm) manufactured by Geomatec Companywas cleaned by ultrasonic cleaning in isopropyl alcohol for 5 min andthen UV ozone cleaning for 30 min.

The cleaned glass substrate was mounted to a substrate holder of avacuum vapor deposition apparatus. The compound C-1 was vapor-depositedby resistance heating so as to cover the transparent electrode to form ahole injecting layer with a thickness of 10 nm adjacent to the anode.

On the hole injecting layer, the compound X4 was vapor-deposited byresistance heating to form a first hole transporting layer with athickness of 65 nm.

On the first hole transporting layer, the compound X3 wasvapor-deposited by resistance heating to form a second hole transportinglayer with a thickness of 10 nm.

On the second hole transporting layer, the compound H5 (first hostmaterial), the compound F2 (second host material), and Ir(bzq)₃(phosphorescent dopant) were co-deposited by resistance heating to forma yellow-light emitting layer with a thickness of 25 nm. Theconcentration in the light emitting layer was 45% by mass for the firsthost material, 45% by mass for the second host material, and 10% by massfor the phosphorescent dopant.

On the light emitting layer, the compound ET was vapor-deposited byresistance heating to form an electron transporting layer with athickness of 35 nm.

Then, LiF was vapor-deposited on the electron transporting layer to forman electron injecting layer with a thickness of 1 nm. Then, metallic Alwas vapor-deposited on the electron injecting layer to form a cathodewith a thickness of 80 nm.

Evaluation of Emission Performance of Organic EL Device

Each of the obtained organic EL devices was measured for the voltage andexternal quantum efficiency at room temperature by driving the device atconstant DC current (current density: 10 mA/cm²) and further measuredfor 90% lifetime (time taken until the luminance was reduced to 90% ofthe initial luminance when driving the device at constant current) at acurrent density of 50 mA/cm². The results are shown in Table 2.

Examples 7 to 17 and Comparative Examples 3 and 6 to 7

Each organic EL device was produced in the same manner as in Example 6except for forming the light emitting layer by using the host material 1and the host material 2 listed in Table 2.

The voltage, emission efficiency and 90% lifetime of the obtainedorganic EL devices are shown in Table 2.

Comparative Examples 2, 4 and 5

Each organic EL device was produced in the same manner as in Example 6except for forming the light emitting layer by using the host material 2(90% by mass) listed in Table 2.

The voltage, emission efficiency and 90% lifetime of the obtainedorganic EL devices are shown in Table 2.

TABLE 2 External 90% Volt- quantum Life- Light emitting layer ageefficiency time Host material 1 Host material 2 (V) (%) (h) Example 6compound H5 compound F2 3.05 20.2 160 Example 7 compound H1 compound F23.27 18.0 120 Example 8 compound H2 compound F2 3.43 19.4 130 Example 9compound H3 compound F2 3.38 19.2 160 Example 10 compound H4 compound F23.42 20.7 120 Example 11 compound H7 compound F2 3.24 20.8 160 Example12 compound H10 compound F2 3.28 22.1 150 Example 13 compound H12compound F2 3.44 20.9 110 Example 14 compound H14 compound F2 3.09 14.6160 Example 15 compound H13 compound F2 3.20 19.9 160 Comparative —compound F2 3.40 20.5 70 Example 2 Comparative compound F1 compound F23.34 22.2 60 Example 3 Example 16 compound H5 compound F4 3.02 20.7 90Comparative — compound F4 3.30 19.8 40 Example 4 Example 17 compound H5compound F5 3.33 22.0 95 Comparative — compound F5 4.10 21.7 11 Example5 Comparative compound F1 compound F5 3.42 22.3 20 Example 6 Comparativecompound F1 compound F6 4.85 13.0 0 Example 7

As seen from Table 2, the organic EL devices of Examples 6 to 15, eachemploying the compound represented by formula (A) as the first hostmaterial and the compound represented by formula (1) as the second hostmaterial, show increased lifetimes as compared with the organic ELdevices of Comparative Examples 2 and 3.

The organic EL devices of Examples 16 and 17, in which the compoundrepresented by formula (A) was used as the first host material and thecompound represented by formula (1) and having one carbazole ring andone azine ring in its molecule was used as the second host material showincreased lifetimes as compared with the organic EL devices ofComparative Examples 4 to 7.

Example 18

Production of Organic EL Device

A glass substrate of 25 mm×75 mm×1.1 mm thickness having an ITOtransparent electrode (anode, 130 nm) manufactured by Geomatec Companywas cleaned by ultrasonic cleaning in isopropyl alcohol for 5 min andthen UV ozone cleaning for 30 min.

The cleaned glass substrate was mounted to a substrate holder of avacuum vapor deposition apparatus. The compound C-1 was vapor-depositedby resistance heating so as to cover the transparent electrode to form ahole injecting layer with a thickness of 5 nm adjacent to the anode.

On the hole injecting layer, the compound X1 was vapor-deposited byresistance heating to form a first hole transporting layer with athickness of 160 nm.

On the first hole transporting layer, the compound X3 wasvapor-deposited by resistance heating to form a second hole transportinglayer with a thickness of 10 nm.

On the second hole transporting layer, the compound H5 (first hostmaterial), the compound F2 (second host material), and Ir(ppy)₃(phosphorescent dopant) were co-deposited by resistance heating to forma green-light emitting layer with a thickness of 25 nm. Theconcentration in the light emitting layer was 45% by mass for the firsthost material, 45% by mass for the second host material, and 10% by massfor the phosphorescent dopant.

On the light emitting layer, the compound ET was vapor-deposited byresistance heating to form an electron transporting layer with athickness of 35 nm.

Then, LiF was vapor-deposited on the electron transporting layer to forman electron injecting layer with a thickness of 1 nm. Then, metallic Alwas vapor-deposited on the electron injecting layer to form a cathodewith a thickness of 80 nm.

Evaluation of Emission Performance of Organic EL Device

Each of the obtained organic EL devices was measured for the voltage andexternal quantum efficiency at room temperature by driving the device atconstant DC current (current density: 10 mA/cm²) and further measuredfor 95% lifetime at an initial luminance of 4,000 cd/m² (time takenuntil the luminance was reduced to 95% of the initial luminance whendriving the device at constant current). The results are shown in Table3.

Examples 19 to 20 and Comparative Example 8

Each organic EL device was produced in the same manner as in Example 18except for forming the light emitting layer by using the host material 1and the host material 2 listed in Table 3.

The voltage, external quantum efficiency and 95% lifetime of theobtained organic EL devices are shown in Table 3.

TABLE 3 External 95% Volt- quantum Life- Light emitting layer ageefficiency time Host material 1 Host material 2 (V) (%) (h) Example 18compound H5 compound F2 3.88 14.9 210 Example 19 compound H3 compound F23.92 15.1 210 Example 20 compound H7 compound F2 3.90 15.3 220Comparative compound F6 compound F2 4.51 13.8 90 Example 8

The organic EL devices of Examples 18 to 20, each employing the compoundrepresented by formula (A) as the first host material and the compoundrepresented by formula (1) as the second host material, show increasedlifetimes as compared with the organic EL device of Comparative Example8.

Examples 21 to 28 and Comparative Examples 9 to 11

Each organic EL device was produced in the same manner as in Example 1except for forming the light emitting layer by using the host material 1and the host material 2 listed in Table 4.

The emission efficiency and 90% lifetime of the obtained organic ELdevices are shown in Table 4.

TABLE 4 External 90% quantum Life- Light emitting layer Voltageefficiency time Host material 1 Host material 2 (V) (%) (h) Example 21compound H7  compound F7  3.11 19.9 170 Example 22 compound H7  compoundF8  3.30 17.5 120 Example 23 compound H7  compound F9  3.14 21.0 140Example 24 compound H7  compound F10 3.20 20.5 150 Example 25 compoundH7  compound F11 3.20 19.8 130 Example 26 compound H15 compound F2  3.6023.0  90 Example 27 compound H16 compound F2  3.61 23.5  90 Example 28compound H17 compound F2  3.55 23.0 100 Comparative — compound F9  3.0019.8  30 Example 9  Comparative — compound F10 3.00 20.0  55 Example 10Comparative — compound F11 3.10 16.9  35 Example 11

Examples 29 to 35 and Comparative Examples 12 to 14

Each organic EL device was produced in the same manner as in Example 18except for forming the light emitting layer by using the host material 1and the host material 2 listed in Table 5.

The voltage, external quantum efficiency and 95% lifetime of theobtained organic EL devices are shown in Table 5.

TABLE 5 External 95% Volt- quantum Life- Light emitting layer ageefficiency time Host material 1 Host material 2 (V) (%) (h) Example 29compound H7 compound F8 3.95 15.0 200 Example 30 compound H7 compound F93.80 14.0 140 Example 31 compound H7 compound F10 3.81 14.2 150 Example32 compound H15 compound F2 4.30 14.0 130 Example 33 compound H16compound F2 4.30 14.1 130 Example 34 compound H17 compound F2 4.25 14.0140 Example 35 compound H17 compound F11 3.80 14.1 140 Comparative —compound F9 3.74 12.0 30 Example 12 Comparative — compound F10 3.74 11.560 Example 13 Comparative — compound F11 3.75 13.6 30 Example 14

INDUSTRIAL APPLICABILITY

As described above in detail, the organic EL device of the inventionexhibits an improved long lifetime.

REFERENCE NUMERALS

-   1: Organic electroluminescence device-   2: Substrate-   3: Anode-   4: Cathode-   5: Phosphorescent light emitting layer-   6: Hole injecting/transporting layer-   7: Electron injecting/transporting layer-   10: Organic thin film layer

What is claimed is:
 1. An organic electroluminescence device whichcomprises a light emitting layer which is disposed between a cathode andan anode and comprises a first host material, a second host material anda light emitting material, wherein the first host material isrepresented by formula (A):

wherein each of A¹ and A² independently represents a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms or a substituted or unsubstituted residue selected from the groupconsisting of a pyrrole ring, an isoindole ring, a benzofuran ring, anisobenzofuran ring, a dibenzothiophene ring, an indole ring, apyrrolidine ring, a dioxane ring, a piperidine ring, a morpholine ring,a piperazine ring, a carbazole ring, a furan ring, a thiophene ring, anoxazole ring, an oxadiazole ring, a benzoxazole ring, a thiazole ring, athiadiazole ring, a benzothiazole ring, a triazole ring, an imidazolering, a benzimidazole ring, a pyran ring, a dibenzofuran ring, and abenzo[c]dibenzofuran ring; A³ represents a divalent monocyclicheterocyclic group having 5 ring atoms; A³ may be independentlysubstituted with at least one group selected from the group consistingof a cyano group, a halogen atom, an alkyl group having 1 to 20 carbonatoms, a cycloalkyl group having 3 to 20 carbon atoms, an alkoxyl grouphaving 1 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbonatoms, a haloalkoxyl group having 1 to 20 carbon atoms, an alkyl silylgroup having 1 to 10 carbon atoms, an aryloxy group having 6 to 30 ringcarbon atoms, an arylsilyl group having 6 to 30 carbon atoms, an aralkylgroup having 6 to 30 carbon atoms, and a heteroaryl group having 5 to 30ring atoms, a phenyl group, a naphthyl group, a biphenyl group, aterphenyl group, a phenanthryl group, a spirobifluorenyl group, atriphenylenyl group, a fluorenyl group, a spirobifluorenyl group, and afluoranthenyl group, m represents an integer of 0 to 3; each of X¹ to X⁸and Y¹ to Y⁸ independently represents N or CR^(a); each of R^(a)independently represents a hydrogen atom, a substituted or unsubstitutedaromatic hydrocarbon group having 6 to 30 ring carbon atoms, asubstituted or unsubstituted heterocyclic group having 5 to 30 ringatoms, a substituted or unsubstituted alkyl group having 1 to 30 carbonatoms, a substituted or unsubstituted silyl group, a halogen atom, or acyano group, provided that when two or more R^(a) groups exist, theR^(a) groups may be the same or different and one of X⁵ to X⁸ and one ofY¹ to Y⁴ are bonded to each other via A³; and the formula (A) satisfiesat least one of the following requirements (i) to (v): (i) at least oneof A¹and A² represents a cyano-substituted aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms or a cyano-substituted group selectedfrom the group consisting of a pyrrole ring, an isoindole ring, abenzofuran ring, an isobenzofuran ring, a dibenzothiophene ring, anindole ring, a pyrrolidine ring, a dioxane ring, a piperidine ring, amorpholine ring, a piperazine ring, a carbazole ring, a furan ring, athiophene ring, an oxazole ring, an oxadiazole ring, a benzoxazole ring,a thiazole ring, a thiadiazole ring, a benzothiazole ring, a triazolering, an imidazole ring, a benzimidazole ring, a pyran ring, adibenzofuran ring, and a benzo[c]dibenzofuran ring; (ii) at least one ofX¹ to X⁴ and Y⁵ to Y⁸ represents CR^(a), and at least one of R^(a) in X¹to X⁴ and Y⁵ to Y⁸ represents a cyano-substituted aromatic hydrocarbongroup having 6 to 30 ring carbon atoms or a cyano-substitutedheterocyclic group having 5 to 30 ring atoms; (iii) m represents aninteger of 1 to 3 and at least one of A³ represents a cyano-substituteddivalent heterocyclic group having 5 ring atoms; (iv) at least one of X⁵to X⁸ and Y¹ to Y⁴ represents CR^(a), and at least one of R^(a) in X⁵ toX⁸ and Y¹ to Y⁸ represents a cyano-substituted aromatic hydrocarbongroup having 6 to 30 ring carbon atoms or a cyano-substitutedheterocyclic group having 5 to 30 ring atoms; and (v) at least one of X¹to X⁸ and Y¹ to Y⁸ represents C—CN; and the second host material isrepresented by formula (1):

wherein Z¹ represents a ring structure fused to a side a and representedby formula (1-1) or (1-2), and Z² represents a ring structure fused to aside b and represented by formula (1-1) or (1-2), provided that at leastone of Z¹ and Z² is represented by formula (1-1):

in formula (1-1), a side c is fused to the side a or b of formula (1);in formula (1-2), any one of sides d, e and f is fused to the side a orb of formula (1); in formulae (1-1) and (1-2), X¹¹ represents a sulfuratom, an oxygen atom, N—R¹⁹, or C(R²⁰)(R²¹); each of R¹¹ to R²¹independently represents a hydrogen atom, a heavy hydrogen atom, ahalogen atom, a cyano group, a substituted or unsubstituted aromatichydrocarbon group having 6 to 30 ring carbon atoms, a substituted orunsubstituted heterocyclic group having 5 to 30 ring atoms, asubstituted or unsubstituted alkyl group having 1 to 30 carbon atoms, asubstituted or unsubstituted alkenyl group having 2 to 30 carbon atoms,a substituted or unsubstituted alkynyl group having 2 to 30 carbonatoms, a substituted or unsubstituted alkylsilyl group having 3 to 30carbon atoms, a substituted or unsubstituted arylsilyl group having 6 to30 ring carbon atoms, a substituted or unsubstituted alkoxy group having1 to 30 carbon atoms, a substituted or unsubstituted aralkyl grouphaving 6 to 30 ring carbon atoms, or a substituted or unsubstitutedaryloxy group having 6 to 30 ring carbon atoms, provided that adjacentgroups of R¹¹ to R²¹ may be bonded to each other to form a a ring; M¹represent a substituted or unsubstituted nitrogen-containing aromaticheteroring having 5 to 30 ring atoms; L¹ represents a single bond, asubstituted or unsubstituted divalent aromatic hydrocarbon group having6 to 30 ring carbon atoms, a substituted or unsubstituted divalentheterocyclic group having 5 to 30 ring atoms, a cycloalkylene grouphaving 5 to 30 ring atoms, or a group in which the preceding groups aredirectly linked to each other; and k represents 1 or
 2. 2. The organicelectroluminescence device according to claim 1, wherein the first hostmaterial satisfies at least one of the requirements (i) and (ii).
 3. Theorganic electroluminescence device according to claim 1, wherein thesecond host material is represented by formula (2):

wherein Z¹ represents a ring structure fused to the side a andrepresented by formula (1-1) or (1-2), and Z² represents a ringstructure fused to the side b and represented by formula (1-1) or (1-2),provided that at least one of Z¹ and Z² is represented by formula (1-1);L¹ is as defined in formula (1); each of X¹² to X¹⁴ independentlyrepresents a nitrogen atom, CH, or a carbon atom bonded to R³¹ or L¹,provided that at least one of X¹² to X¹⁴ represents a nitrogen atom;each of Y¹¹ to Y¹³ independently represents CH or a carbon atom bondedto R³¹ or L¹; each of R³¹ independently represents a halogen atom, acyano group, a substituted or unsubstituted aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms, a substituted or unsubstitutedheterocyclic group having 5 to 30 ring atoms, a substituted orunsubstituted alkyl group having 1 to 30 carbon atoms, a substituted orunsubstituted alkenyl group having 2 to 30 carbon atoms, a substitutedor unsubstituted alkynyl group having 2 to 30 carbon atoms, asubstituted or unsubstituted alkylsilyl group having 3 to 30 carbonatoms, a substituted or unsubstituted arylsilyl group having 6 to 30ring carbon atoms, a substituted or unsubstituted alkoxy group having 1to 30 carbon atoms, a substituted or unsubstituted aralkyl group having6 to 30 ring carbon atoms, or a substituted or unsubstituted aryloxygroup having 6 to 30 ring carbon atoms; when two or more R³¹ groupsexist, the R³¹ groups may be the same or different and adjacent R³¹groups may be bonded to each other to form a ring; k represents 1 or 2,and n represents an integer of 0 to 4; the side c of formula (1-1) isfused to the side a or b of formula (2); and any one of sides d, e and fof formula (1-2) is fused to the side a or b of formula (2).
 4. Theorganic electroluminescence device according to claim 1, wherein thesecond host material is represented by formula (3):

wherein L¹ is as defined in formula (1); each of X¹² to X¹⁴independently represents a nitrogen atom, CH, or a carbon atom bonded toR³¹ or L¹, provided that at least one of X¹² to X¹⁴ represents anitrogen atom; each of Y¹¹ to Y¹³ independently represents CH or acarbon atom bonded to R³¹ or L¹; each of R³¹ independently represents ahalogen atom, a cyano group, a substituted or unsubstituted aromatichydrocarbon group having 6 to 30 ring carbon atoms, a substituted orunsubstituted heterocyclic group having 5 to 30 ring atoms, asubstituted or unsubstituted alkyl group having 1 to 30 carbon atoms, asubstituted or unsubstituted alkenyl group having 2 to 30 carbon atoms,a substituted or unsubstituted alkynyl group having 2 to 30 carbonatoms, a substituted or unsubstituted alkylsilyl group having 3 to 30carbon atoms, a substituted or unsubstituted arylsilyl group having 6 to30 ring carbon atoms, a substituted or unsubstituted alkoxy group having1 to 30 carbon atoms, a substituted or unsubstituted aralkyl grouphaving 6 to 30 ring carbon atoms, or a substituted or unsubstitutedaryloxy group having 6 to 30 ring carbon atoms; when two or more R³¹groups exist, the R³¹ groups may be the same or different and adjacentR³¹ groups may be bonded to each other to form a ring; n represents aninteger of 0 to 4; each of R⁴¹ to R⁴⁸ independently represents ahydrogen atom, a heavy hydrogen atom, a halogen atom, a cyano group, asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, a substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, a substituted or unsubstituted alkyl grouphaving 1 to 30 carbon atoms, a substituted or unsubstituted alkenylgroup having 2 to 30 carbon atoms, a substituted or unsubstitutedalkynyl group having 2 to 30 carbon atoms, a substituted orunsubstituted alkylsilyl group having 3 to 30 carbon atoms, asubstituted or unsubstituted arylsilyl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted alkoxy group having 1 to 30 carbonatoms, a substituted or unsubstituted aralkyl group having 6 to 30 ringcarbon atoms, or a substituted or unsubstituted aryloxy group having 6to 30 ring carbon atoms; and adjacent groups of R⁴¹ to R⁴⁸ may be bondedto each other to form a ring.
 5. The organic electroluminescence deviceaccording to claim 1, wherein the first host material satisfies only therequirement (i).
 6. The organic electroluminescence device according toclaim 1, wherein the second host material is represented by formula (4):

wherein L¹ is as defined in formula (1); each of X¹² to X¹⁴independently represents a nitrogen atom, CH, or a carbon atom bonded toR³¹ or L¹, provided that at least one of X¹² to X¹⁴ represents anitrogen atom; each of Y¹¹ to Y¹³ independently represents CH or acarbon atom bonded to R³¹ or L¹; each of R³¹ independently represents ahalogen atom, a cyano group, a substituted or unsubstituted aromatichydrocarbon group having 6 to 30 ring carbon atoms, a substituted orunsubstituted heterocyclic group having 5 to 30 ring atoms, asubstituted or unsubstituted alkyl group having 1 to 30 carbon atoms, asubstituted or unsubstituted alkenyl group having 2 to 30 carbon atoms,a substituted or unsubstituted alkynyl group having 2 to 30 carbonatoms, a substituted or unsubstituted alkylsilyl group having 3 to 30carbon atoms, a substituted or unsubstituted arylsilyl group having 6 to30 ring carbon atoms, a substituted or unsubstituted alkoxy group having1 to 30 carbon atoms, a substituted or unsubstituted aralkyl grouphaving 6 to 30 ring carbon atoms, or a substituted or unsubstitutedaryloxy group having 6 to 30 ring carbon atoms; when two or more R³¹groups exist, the R³¹ groups may be the same or different and adjacentR³¹ groups may be bonded to each other to form a ring; n represents aninteger of 0 to 4; each of L² and L³ independently represents a singlebond, a substituted or unsubstituted divalent aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms, a substituted or unsubstituteddivalent heterocyclic group having 5 to 30 ring atoms, a cycloalkylenegroup having 5 to 30 ring atoms, or a group in which the precedinggroups are directly linked to each other; each of R⁵¹ to R⁵⁴independently represents a halogen atom, a cyano group, a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms, a substituted or unsubstituted heterocyclic group having 5 to 30ring atoms, a substituted or unsubstituted alkyl group having 1 to 30carbon atoms, a substituted or unsubstituted alkenyl group having 2 to30 carbon atoms, a substituted or unsubstituted alkynyl group having 2to 30 carbon atoms, a substituted or unsubstituted alkylsilyl grouphaving 3 to 30 carbon atoms, a substituted or unsubstituted arylsilylgroup having 6 to 30 ring carbon atoms, a substituted or unsubstitutedalkoxy group having 1 to 30 carbon atoms, a substituted or unsubstitutedaralkyl group having 6 to 30 ring carbon atoms, or a substituted orunsubstituted aryloxy group having 6 to 30 ring carbon atoms; when twoor more R⁵¹ groups exist, the R⁵¹ groups may be the same or differentand adjacent R⁵¹ groups may be bonded to each other to form a ring; whentwo or more R⁵² groups exist, the R⁵² groups may be the same ordifferent and adjacent R⁵² groups may be bonded to each other to form aring; when two or more R⁵³ groups exist, the R⁵³ groups may be the sameor different and adjacent R⁵³ groups may be bonded to each other to forma ring; when two or more R⁵⁴ groups exist, the R⁵⁴ groups may be thesame or different and adjacent R⁵⁴ groups may be bonded to each other toform a ring; M² represents a substituted or unsubstituted aromatichydrocarbon group having 6 to 30 ring carbon atoms or a substituted orunsubstituted heterocyclic group having 5 to 30 ring atoms; and each ofp and s independently represents an integer of 0 to 4, and each of q andr independently represents an integer of 0 to
 3. 7. The organicelectroluminescence device according to claim 1, wherein at least one ofA¹ and A² represents a cyano-substituted phenyl group, acyano-substituted naphthyl group, a cyano-substituted phenanthryl group,a cyano-substituted dibenzofuranyl group, a cyano-substituteddibenzothiophenyl group, a cyano-substituted biphenyl group, acyano-substituted terphenyl group, a cyano-substituted9,9-diphenylfluorenyl group, a cyano-substituted9,9′-spirobi[9H-fluorene]-2-yl group, a cyano-substituted9,9′-dimethylfluorenyl group, or a cyano-substituted triphenylenylgroup.
 8. The organic electroluminescence device according to claim 1,wherein the light emitting material comprises a phosphorescent emittingmaterial selected from ortho metallated complexes of a metal selectedfrom iridium (Ir), osmium (Os), and platinum (Pt).
 9. The organicelectroluminescence device according to claim 1, wherein a peak ofemission wavelength of the phosphorescent emitting material is 490 nm orlonger and 700 nm or shorter.
 10. The organic electroluminescence deviceaccording to claim 1, wherein m of formula (A) represents 0.